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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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---
category:
- Geometry
from: http://rosettacode.org/wiki/Total_circles_area

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Given some partially overlapping circles on the plane, compute and show the total area covered by them, with four or six (or a little more) decimal digits of precision. The area covered by two or more disks needs to be counted only once.
One point of this Task is also to compare and discuss the relative merits of various solution strategies, their performance, precision and simplicity. This means keeping both slower and faster solutions for a language (like C) is welcome.
To allow a better comparison of the different implementations, solve the problem with this standard dataset, each line contains the '''x''' and '''y''' coordinates of the centers of the disks and their radii   (11 disks are fully contained inside other disks):
<pre>
xc yc radius
1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985
</pre>
The result is &nbsp; 21.56503660... .
;Related task:
* &nbsp; [[Circles of given radius through two points]].
;See also:
* http://www.reddit.com/r/dailyprogrammer/comments/zff9o/9062012_challenge_96_difficult_water_droplets/
* http://stackoverflow.com/a/1667789/10562
<br><br>

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T Circle
Float x, y, r
F (x, y, r)
.x = x
.y = y
.r = r
V circles = [
Circle(1.6417233788, 1.6121789534, 0.0848270516),
Circle(-1.4944608174, 1.2077959613, 1.1039549836),
Circle(0.6110294452, -0.6907087527, 0.9089162485),
Circle(0.3844862411, 0.2923344616, 0.2375743054),
Circle(-0.2495892950, -0.3832854473, 1.0845181219),
Circle(1.7813504266, 1.6178237031, 0.8162655711),
Circle(-0.1985249206, -0.8343333301, 0.0538864941),
Circle(-1.7011985145, -0.1263820964, 0.4776976918),
Circle(-0.4319462812, 1.4104420482, 0.7886291537),
Circle(0.2178372997, -0.9499557344, 0.0357871187),
Circle(-0.6294854565, -1.3078893852, 0.7653357688),
Circle(1.7952608455, 0.6281269104, 0.2727652452),
Circle(1.4168575317, 1.0683357171, 1.1016025378),
Circle(1.4637371396, 0.9463877418, 1.1846214562),
Circle(-0.5263668798, 1.7315156631, 1.4428514068),
Circle(-1.2197352481, 0.9144146579, 1.0727263474),
Circle(-0.1389358881, 0.1092805780, 0.7350208828),
Circle(1.5293954595, 0.0030278255, 1.2472867347),
Circle(-0.5258728625, 1.3782633069, 1.3495508831),
Circle(-0.1403562064, 0.2437382535, 1.3804956588),
Circle(0.8055826339, -0.0482092025, 0.3327165165),
Circle(-0.6311979224, 0.7184578971, 0.2491045282),
Circle(1.4685857879, -0.8347049536, 1.3670667538),
Circle(-0.6855727502, 1.6465021616, 1.0593087096),
Circle(0.0152957411, 0.0638919221, 0.9771215985)]
V x_min = min(circles.map(c -> c.x - c.r))
V x_max = max(circles.map(c -> c.x + c.r))
V y_min = min(circles.map(c -> c.y - c.r))
V y_max = max(circles.map(c -> c.y + c.r))
V box_side = 500
V dx = (x_max - x_min) / box_side
V dy = (y_max - y_min) / box_side
V count = 0
L(r) 0 .< box_side
V y = y_min + r * dy
L(c) 0 .< box_side
V x = x_min + c * dx
I any(circles.map(circle -> (@x - circle.x) ^ 2 + (@y - circle.y) ^ 2 <= (circle.r ^ 2)))
count++
print(Approximated area: (count * dx * dy))

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circles: @[
@[ 1.6417233788 1.6121789534 0.0848270516]
@[neg 1.4944608174 1.2077959613 1.1039549836]
@[ 0.6110294452 neg 0.6907087527 0.9089162485]
@[ 0.3844862411 0.2923344616 0.2375743054]
@[neg 0.2495892950 neg 0.3832854473 1.0845181219]
@[ 1.7813504266 1.6178237031 0.8162655711]
@[neg 0.1985249206 neg 0.8343333301 0.0538864941]
@[neg 1.7011985145 neg 0.1263820964 0.4776976918]
@[neg 0.4319462812 1.4104420482 0.7886291537]
@[ 0.2178372997 neg 0.9499557344 0.0357871187]
@[neg 0.6294854565 neg 1.3078893852 0.7653357688]
@[ 1.7952608455 0.6281269104 0.2727652452]
@[ 1.4168575317 1.0683357171 1.1016025378]
@[ 1.4637371396 0.9463877418 1.1846214562]
@[neg 0.5263668798 1.7315156631 1.4428514068]
@[neg 1.2197352481 0.9144146579 1.0727263474]
@[neg 0.1389358881 0.1092805780 0.7350208828]
@[ 1.5293954595 0.0030278255 1.2472867347]
@[neg 0.5258728625 1.3782633069 1.3495508831]
@[neg 0.1403562064 0.2437382535 1.3804956588]
@[ 0.8055826339 neg 0.0482092025 0.3327165165]
@[neg 0.6311979224 0.7184578971 0.2491045282]
@[ 1.4685857879 neg 0.8347049536 1.3670667538]
@[neg 0.6855727502 1.6465021616 1.0593087096]
@[ 0.0152957411 0.0638919221 0.9771215985]
]
xMin: min map circles 'c -> c\0 - c\2
xMax: max map circles 'c -> c\0 + c\2
yMin: min map circles 'c -> c\1 - c\2
yMax: max map circles 'c -> c\1 + c\2
boxSide: 500
dx: (xMax - xMin) / boxSide
dy: (yMax - yMin) / boxSide
count: 0
loop 0..dec boxSide 'r [
y: yMin + r * dy
loop 0..dec boxSide 'c [
x: xMin + c * dx
loop circles 'circle [
if (add (x - first circle)*(x - first circle) (y - circle\1)*(y - circle\1)) =< (last circle)*(last circle) [
count: count + 1
break
]
]
]
]
print ["Approximated area: " count * dx * dy]

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#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#include <stdbool.h>
typedef double Fp;
typedef struct { Fp x, y, r; } Circle;
Circle circles[] = {
{ 1.6417233788, 1.6121789534, 0.0848270516},
{-1.4944608174, 1.2077959613, 1.1039549836},
{ 0.6110294452, -0.6907087527, 0.9089162485},
{ 0.3844862411, 0.2923344616, 0.2375743054},
{-0.2495892950, -0.3832854473, 1.0845181219},
{ 1.7813504266, 1.6178237031, 0.8162655711},
{-0.1985249206, -0.8343333301, 0.0538864941},
{-1.7011985145, -0.1263820964, 0.4776976918},
{-0.4319462812, 1.4104420482, 0.7886291537},
{ 0.2178372997, -0.9499557344, 0.0357871187},
{-0.6294854565, -1.3078893852, 0.7653357688},
{ 1.7952608455, 0.6281269104, 0.2727652452},
{ 1.4168575317, 1.0683357171, 1.1016025378},
{ 1.4637371396, 0.9463877418, 1.1846214562},
{-0.5263668798, 1.7315156631, 1.4428514068},
{-1.2197352481, 0.9144146579, 1.0727263474},
{-0.1389358881, 0.1092805780, 0.7350208828},
{ 1.5293954595, 0.0030278255, 1.2472867347},
{-0.5258728625, 1.3782633069, 1.3495508831},
{-0.1403562064, 0.2437382535, 1.3804956588},
{ 0.8055826339, -0.0482092025, 0.3327165165},
{-0.6311979224, 0.7184578971, 0.2491045282},
{ 1.4685857879, -0.8347049536, 1.3670667538},
{-0.6855727502, 1.6465021616, 1.0593087096},
{ 0.0152957411, 0.0638919221, 0.9771215985}};
const size_t n_circles = sizeof(circles) / sizeof(Circle);
static inline Fp min(const Fp a, const Fp b) { return a <= b ? a : b; }
static inline Fp max(const Fp a, const Fp b) { return a >= b ? a : b; }
static inline Fp sq(const Fp a) { return a * a; }
// Return an uniform random value in [a, b).
static inline double uniform(const double a, const double b) {
const double r01 = rand() / (double)RAND_MAX;
return a + (b - a) * r01;
}
static inline bool is_inside_circles(const Fp x, const Fp y) {
for (size_t i = 0; i < n_circles; i++)
if (sq(x - circles[i].x) + sq(y - circles[i].y) < circles[i].r)
return true;
return false;
}
int main() {
// Initialize the bounding box (bbox) of the circles.
Fp x_min = INFINITY, x_max = -INFINITY;
Fp y_min = x_min, y_max = x_max;
// Compute the bounding box of the circles.
for (size_t i = 0; i < n_circles; i++) {
Circle *c = &circles[i];
x_min = min(x_min, c->x - c->r);
x_max = max(x_max, c->x + c->r);
y_min = min(y_min, c->y - c->r);
y_max = max(y_max, c->y + c->r);
c->r *= c->r; // Square the radii to speed up testing.
}
const Fp bbox_area = (x_max - x_min) * (y_max - y_min);
// Montecarlo sampling.
srand(time(0));
size_t to_try = 1U << 16;
size_t n_tries = 0;
size_t n_hits = 0;
while (true) {
n_hits += is_inside_circles(uniform(x_min, x_max),
uniform(y_min, y_max));
n_tries++;
if (n_tries == to_try) {
const Fp area = bbox_area * n_hits / n_tries;
const Fp r = (Fp)n_hits / n_tries;
const Fp s = area * sqrt(r * (1 - r) / n_tries);
printf("%.4f +/- %.4f (%zd samples)\n", area, s, n_tries);
if (s * 3 <= 1e-3) // Stop at 3 sigmas.
break;
to_try *= 2;
}
}
return 0;
}

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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
typedef double flt;
typedef struct {
flt x, y, r, r2;
flt y0, y1; // extent of circle y+r and y-r
flt x0, x1; // where scanline intersects circle
} circle_t;
#define SZ sizeof(circle_t)
circle_t circles[] = {
{ 1.6417233788, 1.6121789534, 0.0848270516},
#error data snipped for space; copy from previous C example
};
flt max(flt x, flt y) { return x < y ? y : x; }
flt min(flt x, flt y) { return x > y ? y : x; }
flt sq(flt x) { return x * x; }
flt cdist(circle_t *c1, circle_t *c2) {
return sqrt(sq(c1->x - c2->x) + sq(c1->y - c2->y));
}
inline void swap_c(circle_t *c)
{
circle_t tmp = c[0];
c[0] = c[1], c[1] = tmp;
}
flt area(circle_t *circs, int n_circ, flt ymin, flt ymax, flt step)
{
int i, n = n_circ;
circle_t *c = malloc(SZ * n);
memcpy(c, circs, SZ * n);
while (n--)
for (i = 0; i < n; i++)
if (c[i].y1 < c[i+1].y1) swap_c(c + i);
flt total = 0;
int row = 1 + ceil((ymax - ymin) / step);
while (row--) {
flt y = ymin + step * row;
for (n = 0; n < n_circ; n++)
if (y >= c[n].y1) // rest of circles below scanline, ignore
break;
else if (y > c[n].y0) {
flt dx = sqrt(c[n].r2 - sq(y - c[n].y));
c[n].x0 = c[n].x - dx;
c[n].x1 = c[n].x + dx;
// keep circles sorted by left intersection
for (i = n; i-- && c[i].x0 > c[i+1].x0; swap_c(c + i));
} else {// remove a circle when scanline has passed it
memmove(c + n, c + n + 1, SZ * (--n_circ - n));
n--;
}
if (!n) continue;
flt right = c->x1;
total += c->x1 - c->x0;
for (i = 1; i < n; i++) {
if (c[i].x1 <= right) continue;
total += c[i].x1 - max(c[i].x0, right);
right = c[i].x1;
}
}
free(c);
return total * step;
}
int main(void)
{
int n_circ = sizeof(circles) / SZ;
flt ymin = INFINITY, ymax = -INFINITY;
circle_t *c1, *c2;
for (c1 = circles + n_circ; c1-- > circles; ) {
for (c2 = circles + n_circ; c2-- > circles; )
// throw out circles inside another circle
if (c1 != c2 && cdist(c1, c2) + c1->r <= c2->r) {
*c1 = circles[--n_circ];
break;
}
ymin = min(ymin, c1->y0 = c1->y - c1->r);
ymax = max(ymax, c1->y1 = c1->y + c1->r);
c1->r2 = sq(c1->r);
}
flt s = 1. / (1 << 20);
flt y0 = floor(ymin / s) * s;
flt a = area(circles, n_circ, y0, ymax, s);
int nlines = (ymax - y0) / s;
// roughly, it cease to make sense if sqrt(nlines) * 1e-14 >> s * s
printf("area = %.10f\tat %d scanlines\n", a, nlines);
return 0;
}

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import std.stdio, std.math, std.algorithm, std.typecons, std.range;
alias Fp = real;
struct Circle { Fp x, y, r; }
void removeInternalDisks(ref Circle[] circles) pure nothrow @safe {
static bool isFullyInternal(in Circle c1, in Circle c2)
pure nothrow @safe @nogc {
if (c1.r > c2.r) // Quick exit.
return false;
return (c1.x - c2.x) ^^ 2 + (c1.y - c2.y) ^^ 2 <
(c2.r - c1.r) ^^ 2;
}
// Heuristics for performance: large radii first.
circles.sort!q{ a.r > b.r };
// Remove circles inside another circle.
for (auto i = circles.length; i-- > 0; )
for (auto j = circles.length; j-- > 0; )
if (i != j && isFullyInternal(circles[i], circles[j])) {
circles[i] = circles[$ - 1];
circles.length--;
break;
}
}
void main() {
Circle[] circles = [
{ 1.6417233788, 1.6121789534, 0.0848270516},
{-1.4944608174, 1.2077959613, 1.1039549836},
{ 0.6110294452, -0.6907087527, 0.9089162485},
{ 0.3844862411, 0.2923344616, 0.2375743054},
{-0.2495892950, -0.3832854473, 1.0845181219},
{ 1.7813504266, 1.6178237031, 0.8162655711},
{-0.1985249206, -0.8343333301, 0.0538864941},
{-1.7011985145, -0.1263820964, 0.4776976918},
{-0.4319462812, 1.4104420482, 0.7886291537},
{ 0.2178372997, -0.9499557344, 0.0357871187},
{-0.6294854565, -1.3078893852, 0.7653357688},
{ 1.7952608455, 0.6281269104, 0.2727652452},
{ 1.4168575317, 1.0683357171, 1.1016025378},
{ 1.4637371396, 0.9463877418, 1.1846214562},
{-0.5263668798, 1.7315156631, 1.4428514068},
{-1.2197352481, 0.9144146579, 1.0727263474},
{-0.1389358881, 0.1092805780, 0.7350208828},
{ 1.5293954595, 0.0030278255, 1.2472867347},
{-0.5258728625, 1.3782633069, 1.3495508831},
{-0.1403562064, 0.2437382535, 1.3804956588},
{ 0.8055826339, -0.0482092025, 0.3327165165},
{-0.6311979224, 0.7184578971, 0.2491045282},
{ 1.4685857879, -0.8347049536, 1.3670667538},
{-0.6855727502, 1.6465021616, 1.0593087096},
{ 0.0152957411, 0.0638919221, 0.9771215985}];
writeln("Input Circles: ", circles.length);
removeInternalDisks(circles);
writeln("Circles left: ", circles.length);
immutable Fp xMin = reduce!((acc, c) => min(acc, c.x - c.r))
(Fp.max, circles[]);
immutable Fp xMax = reduce!((acc, c) => max(acc, c.x + c.r))
(Fp(0), circles[]);
alias YRange = Tuple!(Fp,"y0", Fp,"y1");
auto yRanges = new YRange[circles.length];
Fp computeTotalArea(in Fp nSlicesX) nothrow @safe {
Fp total = 0;
// Adapted from an idea by Cosmologicon.
foreach (immutable p; cast(int)(xMin * nSlicesX) ..
cast(int)(xMax * nSlicesX) + 1) {
immutable Fp x = p / nSlicesX;
size_t nPairs = 0;
// Look for the circles intersecting the current
// vertical secant:
foreach (const ref c; circles) {
immutable Fp d = c.r ^^ 2 - (c.x - x) ^^ 2;
immutable Fp sd = d.sqrt;
if (d > 0)
// And keep only the intersection chords.
yRanges[nPairs++] = YRange(c.y - sd, c.y + sd);
}
// Merge the ranges, counting the overlaps only once.
yRanges[0 .. nPairs].sort();
Fp y = -Fp.max;
foreach (immutable r; yRanges[0 .. nPairs])
if (y < r.y1) {
total += r.y1 - max(y, r.y0);
y = r.y1;
}
}
return total / nSlicesX;
}
// Iterate to reach some precision.
enum Fp epsilon = 1e-9;
Fp nSlicesX = 1_000;
Fp oldArea = -1;
while (true) {
immutable Fp newArea = computeTotalArea(nSlicesX);
if (abs(oldArea - newArea) < epsilon) {
writeln("N. vertical slices: ", nSlicesX);
writefln("Approximate area: %.17f", newArea);
return;
}
oldArea = newArea;
nSlicesX *= 2;
}
}

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import std.stdio, std.typecons, std.math, std.algorithm, std.range;
struct Vec { double x, y; }
alias VF = double function(in Vec, in Vec) pure nothrow @safe @nogc;
enum VF vCross = (v1, v2) => v1.x * v2.y - v1.y * v2.x;
enum VF vDot = (v1, v2) => v1.x * v2.x + v1.y * v2.y;
alias VV = Vec function(in Vec, in Vec) pure nothrow @safe @nogc;
enum VV vAdd = (v1, v2) => Vec(v1.x + v2.x, v1.y + v2.y);
enum VV vSub = (v1, v2) => Vec(v1.x - v2.x, v1.y - v2.y);
enum vLen = (in Vec v) pure nothrow @safe @nogc => vDot(v, v).sqrt;
enum VF vDist = (a, b) => vSub(a, b).vLen;
enum vScale = (in double s, in Vec v) pure nothrow @safe @nogc =>
Vec(v.x * s, v.y * s);
enum vNorm = (in Vec v) pure nothrow @safe @nogc =>
Vec(v.x / v.vLen, v.y / v.vLen);
alias A = Typedef!double;
enum vAngle = (in Vec v) pure nothrow @safe @nogc => atan2(v.y, v.x).A;
A aNorm(in A a) pure nothrow @safe @nogc {
if (a > PI) return A(a - PI * 2.0);
if (a < -PI) return A(a + PI * 2.0);
return a;
}
struct Circle { double x, y, r; }
A[] circleCross(in Circle c0, in Circle c1) pure nothrow {
immutable d = vDist(Vec(c0.x, c0.y), Vec(c1.x, c1.y));
if (d >= c0.r + c1.r || d <= abs(c0.r - c1.r))
return [];
immutable s = (c0.r + c1.r + d) / 2.0;
immutable a = sqrt(s * (s - d) * (s - c0.r) * (s - c1.r));
immutable h = 2.0 * a / d;
immutable dr = Vec(c1.x - c0.x, c1.y - c0.y);
immutable dx = vScale(sqrt(c0.r ^^ 2 - h ^^ 2), dr.vNorm);
immutable ang = (c0.r ^^ 2 + d ^^ 2 > c1.r ^^ 2) ?
dr.vAngle :
A(PI + dr.vAngle);
immutable da = asin(h / c0.r).A;
return [A(ang - da), A(ang + da)].map!aNorm.array;
}
// Angles of the start and end points of the circle arc.
alias Angle2 = Tuple!(A,"a0", A,"a1");
alias Arc = Tuple!(Circle,"c", Angle2,"aa");
enum arcPoint = (in Circle c, in A a) pure nothrow @safe @nogc =>
vAdd(Vec(c.x, c.y), Vec(c.r * cos(cast(double)a),
c.r * sin(cast(double)a)));
alias ArcF = Vec function(in Arc) pure nothrow @safe @nogc;
enum ArcF arcStart = ar => arcPoint(ar.c, ar.aa.a0);
enum ArcF arcMid = ar => arcPoint(ar.c, A((ar.aa.a0+ar.aa.a1) / 2));
enum ArcF arcEnd = ar => arcPoint(ar.c, ar.aa.a1);
enum ArcF arcCenter = ar => Vec(ar.c.x, ar.c.y);
enum arcArea = (in Arc ar) pure nothrow @safe @nogc =>
ar.c.r ^^ 2 * (ar.aa.a1 - ar.aa.a0) / 2.0;
Arc[] splitCircles(immutable Circle[] cs) pure /*nothrow*/ {
static enum cSplit = (in Circle c, in A[] angs) pure nothrow =>
c.repeat.zip(angs.zip(angs.dropOne).map!Angle2).map!Arc;
// If an arc that was part of one circle is inside *another* circle,
// it will not be part of the zero-winding path, so reject it.
static bool inCircle(VC)(in VC vc, in Circle c) pure nothrow @nogc{
return vc[1] != c && vDist(Vec(vc[0].x, vc[0].y),
Vec(c.x, c.y)) < c.r;
}
enum inAnyCircle = (in Arc arc) nothrow @safe =>
cs.map!(c => inCircle(tuple(arc.arcMid, arc.c), c)).any;
auto f(in Circle c) pure nothrow {
auto angs = cs.map!(c1 => circleCross(c, c1)).join;
return tuple(c, ([A(-PI), A(PI)] ~ angs)
.sort().release);
}
return cs.map!f.map!(ca => cSplit(ca[])).join
.filter!(ar => !inAnyCircle(ar)).array;
}
/** Given a list of arcs, build sets of closed paths from them. If
one arc's end point is no more than 1e-4 from another's start point,
they are considered connected. Since these start/end points resulted
from intersecting circles earlier, they *should* be exactly the same,
but floating point precision may cause small differences, hence the
1e-4 error margin. When there are genuinely different intersections
closer than this margin, the method will backfire, badly. */
const(Arc[])[] makePaths(in Arc[] arcs) pure nothrow @safe {
static const(Arc[])[] joinArcs(in Arc[] a, in Arc[] xxs)
pure nothrow {
static enum eps = 1e-4;
if (xxs.empty) return [a];
immutable x = xxs[0];
const xs = xxs.dropOne;
if (a.empty) return joinArcs([x], xs);
if (vDist(a[0].arcStart, a.back.arcEnd) < eps)
return [a] ~ joinArcs([], xxs);
if (vDist(a.back.arcEnd, x.arcStart) < eps)
return joinArcs(a ~ [x], xs);
return joinArcs(a, xs ~ [x]);
}
return joinArcs([], arcs);
}
// Slice N-polygon into N-2 triangles.
double polylineArea(in Vec[] vvs) pure nothrow {
static enum triArea = (in Vec a, in Vec b, in Vec c)
pure nothrow @nogc => vCross(vSub(b, a), vSub(c, b)) / 2.0;
const vs = vvs.dropOne;
immutable vvs0 = vvs[0];
return zip(vs, vs.dropOne).map!(vv => triArea(vvs0, vv[])).sum;
}
double pathArea(in Arc[] arcs) pure nothrow {
static f(in Tuple!(double, const(Vec)[]) ae, in Arc arc)
pure nothrow {
return tuple(ae[0] + arc.arcArea,
ae[1] ~ [arc.arcCenter, arc.arcEnd]);
}
const ae = reduce!f(tuple(0.0, (const(Vec)[]).init), arcs);
return ae[0] + ae[1].polylineArea;
}
enum circlesArea = (immutable Circle[] cs) pure /*nothrow*/ =>
cs.splitCircles.makePaths.map!pathArea.sum;
void main() {
immutable circles = [
Circle( 1.6417233788, 1.6121789534, 0.0848270516),
Circle(-1.4944608174, 1.2077959613, 1.1039549836),
Circle( 0.6110294452, -0.6907087527, 0.9089162485),
Circle( 0.3844862411, 0.2923344616, 0.2375743054),
Circle(-0.2495892950, -0.3832854473, 1.0845181219),
Circle( 1.7813504266, 1.6178237031, 0.8162655711),
Circle(-0.1985249206, -0.8343333301, 0.0538864941),
Circle(-1.7011985145, -0.1263820964, 0.4776976918),
Circle(-0.4319462812, 1.4104420482, 0.7886291537),
Circle( 0.2178372997, -0.9499557344, 0.0357871187),
Circle(-0.6294854565, -1.3078893852, 0.7653357688),
Circle( 1.7952608455, 0.6281269104, 0.2727652452),
Circle( 1.4168575317, 1.0683357171, 1.1016025378),
Circle( 1.4637371396, 0.9463877418, 1.1846214562),
Circle(-0.5263668798, 1.7315156631, 1.4428514068),
Circle(-1.2197352481, 0.9144146579, 1.0727263474),
Circle(-0.1389358881, 0.1092805780, 0.7350208828),
Circle( 1.5293954595, 0.0030278255, 1.2472867347),
Circle(-0.5258728625, 1.3782633069, 1.3495508831),
Circle(-0.1403562064, 0.2437382535, 1.3804956588),
Circle( 0.8055826339, -0.0482092025, 0.3327165165),
Circle(-0.6311979224, 0.7184578971, 0.2491045282),
Circle( 1.4685857879, -0.8347049536, 1.3670667538),
Circle(-0.6855727502, 1.6465021616, 1.0593087096),
Circle( 0.0152957411, 0.0638919221, 0.9771215985)];
writefln("Area: %1.13f", circles.circlesArea);
}

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type TCircle = record
X,Y: double;
R: double;
end;
const Circles: array [0..24] of TCircle =(
(X: 1.6417233788; Y: 1.6121789534; R: 0.0848270516),
(X: -1.4944608174; Y: 1.2077959613; R: 1.1039549836),
(X: 0.6110294452; Y: -0.6907087527; R: 0.9089162485),
(X: 0.3844862411; Y: 0.2923344616; R: 0.2375743054),
(X: -0.2495892950; Y: -0.3832854473; R: 1.0845181219),
(X: 1.7813504266; Y: 1.6178237031; R: 0.8162655711),
(X: -0.1985249206; Y: -0.8343333301; R: 0.0538864941),
(X: -1.7011985145; Y: -0.1263820964; R: 0.4776976918),
(X: -0.4319462812; Y: 1.4104420482; R: 0.7886291537),
(X: 0.2178372997; Y: -0.9499557344; R: 0.0357871187),
(X: -0.6294854565; Y: -1.3078893852; R: 0.7653357688),
(X: 1.7952608455; Y: 0.6281269104; R: 0.2727652452),
(X: 1.4168575317; Y: 1.0683357171; R: 1.1016025378),
(X: 1.4637371396; Y: 0.9463877418; R: 1.1846214562),
(X: -0.5263668798; Y: 1.7315156631; R: 1.4428514068),
(X: -1.2197352481; Y: 0.9144146579; R: 1.0727263474),
(X: -0.1389358881; Y: 0.1092805780; R: 0.7350208828),
(X: 1.5293954595; Y: 0.0030278255; R: 1.2472867347),
(X: -0.5258728625; Y: 1.3782633069; R: 1.3495508831),
(X: -0.1403562064; Y: 0.2437382535; R: 1.3804956588),
(X: 0.8055826339; Y: -0.0482092025; R: 0.3327165165),
(X: -0.6311979224; Y: 0.7184578971; R: 0.2491045282),
(X: 1.4685857879; Y: -0.8347049536; R: 1.3670667538),
(X: -0.6855727502; Y: 1.6465021616; R: 1.0593087096),
(X: 0.0152957411; Y: 0.0638919221; R: 0.9771215985)
);
procedure CalculateCircleArea(Memo: TMemo; BoxPoints: integer = 500);
var MinX,MinY,MaxX,MaxY,Area: double;
var X,Y,BoxScaleX,BoxScaleY: double;
var I,Row,Col,Count: integer;
var Circle: TCircle;
begin
{Get minimum and maximum size of all the circles}
MinX:=MaxDouble; MinY:=MaxDouble;
MaxX:=MinDouble; MaxY:=MinDouble;
for I:=0 to High(Circles) do
begin
Circle:=Circles[I];
MinX:=min(MinX,Circle.X - Circle.R);
MaxX:=max(MaxX,Circle.X + Circle.R);
MinY:=min(MinY,Circle.Y - Circle.R);
MaxY:=max(MaxY,Circle.Y + Circle.R);
end;
{Calculate scaling factor for X/Y dimension of box}
BoxScaleX:=(MaxX - MinX) / BoxPoints;
BoxScaleY:=(MaxY - MinY) / BoxPoints;
Count:=0;
{Iterate through all X/Y BoxPoints}
for Row:=0 to BoxPoints-1 do
begin
{Get scaled and offset Y pos}
Y:=MinY + Row * BoxScaleY;
for Col:=0 to BoxPoints-1 do
begin
{Get scaled and offset X pos}
X:=MinX + Col * BoxScaleX;
for I:=0 to High(Circles) do
begin
Circle:=Circles[I];
{Check to see if point is in circle}
if (sqr(X - Circle.X) + sqr(Y - Circle.Y)) <= (Sqr(Circle.R)) then
begin
Inc(Count);
{Only count one circle}
break;
end;
end;
end;
end;
{Calculate area from the box scale}
Area:=Count * BoxScaleX * BoxScaleY;
{Display it}
Memo.Lines.Add(Format('Side: %5d Points: %9.0n Area: %3.18f',[BoxPoints,BoxPoints*BoxPoints+0.0,Area]));
end;
procedure TotalCirclesArea(Memo: TMemo);
begin
CalculateCircleArea(Memo, 500);
CalculateCircleArea(Memo, 1000);
CalculateCircleArea(Memo, 1500);
CalculateCircleArea(Memo, 5000);
end;

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(lib 'math)
(define (make-circle x0 y0 r)
(vector x0 y0 r ))
(define-syntax-id _.radius (_ 2))
(define-syntax-id _.x0 (_ 0))
(define-syntax-id _.y0 (_ 1))
;; to sort circles
(define (cmp-circles a b) (> a.radius b.radius))
(define (included? circle: a circles)
(for/or ((b circles))
#:continue (equal? a b)
(disk-in-disk? a b)))
;; eliminates, and sort
(define (sort-circles circles)
(list-sort cmp-circles
(filter (lambda(c) (not (included? c circles))) circles)))
(define circles (sort-circles
(list (make-circle 1.6417233788 1.6121789534 0.0848270516)
(make-circle -1.4944608174 1.2077959613 1.1039549836)
(make-circle 0.6110294452 -0.6907087527 0.9089162485)
(make-circle 0.3844862411 0.2923344616 0.2375743054)
(make-circle -0.2495892950 -0.3832854473 1.0845181219)
(make-circle 1.7813504266 1.6178237031 0.8162655711)
(make-circle -0.1985249206 -0.8343333301 0.0538864941)
(make-circle -1.7011985145 -0.1263820964 0.4776976918)
(make-circle -0.4319462812 1.4104420482 0.7886291537)
(make-circle 0.2178372997 -0.9499557344 0.0357871187)
(make-circle -0.6294854565 -1.3078893852 0.7653357688)
(make-circle 1.7952608455 0.6281269104 0.2727652452)
(make-circle 1.4168575317 1.0683357171 1.1016025378)
(make-circle 1.4637371396 0.9463877418 1.1846214562)
(make-circle -0.5263668798 1.7315156631 1.4428514068)
(make-circle -1.2197352481 0.9144146579 1.0727263474)
(make-circle -0.1389358881 0.1092805780 0.7350208828)
(make-circle 1.5293954595 0.0030278255 1.2472867347)
(make-circle -0.5258728625 1.3782633069 1.3495508831)
(make-circle -0.1403562064 0.2437382535 1.3804956588)
(make-circle 0.8055826339 -0.0482092025 0.3327165165)
(make-circle -0.6311979224 0.7184578971 0.2491045282)
(make-circle 1.4685857879 -0.8347049536 1.3670667538)
(make-circle -0.6855727502 1.6465021616 1.0593087096)
(make-circle 0.0152957411 0.0638919221 0.9771215985))))
;; bounding box
(define (enclosing-rect circles)
(define xmin (for/min ((c circles)) (- c.x0 c.radius)))
(define xmax (for/max ((c circles)) (+ c.x0 c.radius)))
(define ymin (for/min ((c circles)) (- c.y0 c.radius)))
(define ymax (for/max ((c circles)) (+ c.y0 c.radius)))
(vector xmin ymin (- xmax xmin) (- ymax ymin)))
;; Compute surface of entirely overlapped tiles
;; and assign candidates circles to other tiles.
;; cands is a vector nsteps x nsteps of circles lists indexed by (i,j)
(define (S0 circles rect steps into: cands)
(define dx (// (rect 2) steps)) ;; width / steps
(define dy (// (rect 3) steps)) ;; height / steps
(define ds (* dx dy)) ;; tile surface
(define dr (vector (- rect.x0 dx) (- rect.y0 dy) dx dy))
(define ijdx 0)
(for/sum ((i steps))
(vector+= dr 0 dx)
(vector-set! dr 1 (- rect.y0 dy))
(for/sum ((j steps))
(vector+= dr 1 dy)
(set! ijdx (+ i (* j steps)))
(for/sum ((c circles))
#:break (rect-in-disk? dr c) ;; enclosed ? add ds
=> (begin (vector-set! cands ijdx null) ds)
#:continue (not (rect-disk-intersect? dr c))
;; intersects ? add circle to candidates for this tile
(vector-set! cands ijdx (cons c (cands ijdx )))
0)
)))
(define ct 0)
;; return sum of surfaces of tiles which are not entirely overlapped
(define (S circles rect steps cands)
(++ ct)
(define dx (// (rect 2) steps))
(define dy (// (rect 3) steps))
(define ds (* dx dy))
(define dr (vector (- rect.x0 dx) (- rect.y0 dy) dx dy))
(define ijdx 0)
(for/sum ((i steps))
(vector+= dr 0 dx)
(vector-set! dr 1 (- (rect 1) dy))
(for/sum ((j steps))
(vector+= dr 1 dy)
(when (!null? cands) (set! circles (cands (+ i (* j steps)))))
#:continue (null? circles)
;; add surface
(or
(for/or ((c circles)) ;; enclosed ? add ds
#:break (rect-in-disk? dr c) => ds
#f )
(if ;; not intersecting? add 0
(for/or ((c circles))
(rect-disk-intersect? dr c)) #f 0)
;; intersecting ? recurse until precision
(when (> dx s-precision) (S circles dr 2 null))
;; no hope - add ds/2
(// ds 2))
)))

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#define dx 0.0001
'read in the data; I reordered them in descending order of radius
'This maximises our chance of being able to break early, saving run time,
'and we needn't bother finding out which circles are entirely inside others
data -0.5263668798,1.7315156631,1.4428514068
data -0.1403562064,0.2437382535,1.3804956588
data 1.4685857879,-0.8347049536,1.3670667538
data -0.5258728625,1.3782633069,1.3495508831
data 1.5293954595,0.0030278255,1.2472867347
data 1.4637371396,0.9463877418,1.1846214562
data -1.4944608174,1.2077959613,1.1039549836
data 1.4168575317,1.0683357171,1.1016025378
data -0.249589295,-0.3832854473,1.0845181219
data -1.2197352481,0.9144146579,1.0727263474
data -0.6855727502,1.6465021616,1.0593087096
data 0.0152957411,0.0638919221,0.9771215985
data 0.6110294452,-0.6907087527,0.9089162485
data 1.7813504266,1.6178237031,0.8162655711
data -0.4319462812,1.4104420482,0.7886291537
data -0.6294854565,-1.3078893852,0.7653357688
data -0.1389358881,0.109280578,0.7350208828
data -1.7011985145,-0.1263820964,0.4776976918
data 0.8055826339,-0.0482092025,0.3327165165
data 1.7952608455,0.6281269104,0.2727652452
data -0.6311979224,0.7184578971,0.2491045282
data 0.3844862411,0.2923344616,0.2375743054
data 1.6417233788,1.6121789534,0.0848270516
data -0.1985249206,-0.8343333301,0.0538864941
data 0.2178372997,-0.9499557344,0.0357871187
function dist(x0 as double, y0 as double, x1 as double, y1 as double) as double
'distance between two points in 2d space
return sqr( (x1-x0)^2 + (y1-y0)^2 )
end function
dim as double x(1 to 25), y(1 to 25), r(1 to 25), gx, gy, A0, A1, A2, A
dim as integer i, cx, cy
for i = 1 to 25
read x(i), y(i), r(i)
next i
for gx = -2.6 to 2.9 step dx 'sample points on a grid
cx += 1
for gy = -2.3 to 3.2 step dx
cy += 1
for i = 1 to 25
if dist(gx, gy, x(i), y(i)) <= r(i) then
'if our grid point is in the circle
A2 += dx^2 'add the area of a grid square
if cx mod 2 = 0 and cy mod 2 = 0 then A1 += 4*dx^2
if cx mod 4 = 0 and cy mod 4 = 0 then A0 += 16*dx^2
'also keep track of coarser grid areas of twice and four times the size
'You'll see why in a moment
exit for
end if
next i
next gy
next gx
'use Shanks method to refine our estimate of the area
A = (A0*A2-A1^2) / (A0 + A2 - 2*A1)
print A0, A1, A2, A

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package main
import (
"flag"
"fmt"
"math"
"runtime"
"sort"
)
// Note, the standard "image" package has Point and Rectangle but we
// can't use them here since they're defined using int rather than
// float64.
type Circle struct{ X, Y, R, rsq float64 }
func NewCircle(x, y, r float64) Circle {
// We pre-calculate r² as an optimization
return Circle{x, y, r, r * r}
}
func (c Circle) ContainsPt(x, y float64) bool {
return distSq(x, y, c.X, c.Y) <= c.rsq
}
func (c Circle) ContainsC(c2 Circle) bool {
return distSq(c.X, c.Y, c2.X, c2.Y) <= (c.R-c2.R)*(c.R-c2.R)
}
func (c Circle) ContainsR(r Rect) (full, corner bool) {
nw := c.ContainsPt(r.NW())
ne := c.ContainsPt(r.NE())
sw := c.ContainsPt(r.SW())
se := c.ContainsPt(r.SE())
return nw && ne && sw && se, nw || ne || sw || se
}
func (c Circle) North() (float64, float64) { return c.X, c.Y + c.R }
func (c Circle) South() (float64, float64) { return c.X, c.Y - c.R }
func (c Circle) West() (float64, float64) { return c.X - c.R, c.Y }
func (c Circle) East() (float64, float64) { return c.X + c.R, c.Y }
type Rect struct{ X1, Y1, X2, Y2 float64 }
func (r Rect) Area() float64 { return (r.X2 - r.X1) * (r.Y2 - r.Y1) }
func (r Rect) NW() (float64, float64) { return r.X1, r.Y2 }
func (r Rect) NE() (float64, float64) { return r.X2, r.Y2 }
func (r Rect) SW() (float64, float64) { return r.X1, r.Y1 }
func (r Rect) SE() (float64, float64) { return r.X2, r.Y1 }
func (r Rect) Centre() (float64, float64) {
return (r.X1 + r.X2) / 2.0, (r.Y1 + r.Y2) / 2.0
}
func (r Rect) ContainsPt(x, y float64) bool {
return r.X1 <= x && x < r.X2 &&
r.Y1 <= y && y < r.Y2
}
func (r Rect) ContainsPC(c Circle) bool { // only N,W,E,S points of circle
return r.ContainsPt(c.North()) ||
r.ContainsPt(c.South()) ||
r.ContainsPt(c.West()) ||
r.ContainsPt(c.East())
}
func (r Rect) MinSide() float64 {
return math.Min(r.X2-r.X1, r.Y2-r.Y1)
}
func distSq(x1, y1, x2, y2 float64) float64 {
Δx, Δy := x2-x1, y2-y1
return (Δx * Δx) + (Δy * Δy)
}
type CircleSet []Circle
// sort.Interface for sorting by radius big to small:
func (s CircleSet) Len() int { return len(s) }
func (s CircleSet) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s CircleSet) Less(i, j int) bool { return s[i].R > s[j].R }
func (sp *CircleSet) RemoveContainedC() {
s := *sp
sort.Sort(s)
for i := 0; i < len(s); i++ {
for j := i + 1; j < len(s); {
if s[i].ContainsC(s[j]) {
s[j], s[len(s)-1] = s[len(s)-1], s[j]
s = s[:len(s)-1]
} else {
j++
}
}
}
*sp = s
}
func (s CircleSet) Bounds() Rect {
x1 := s[0].X - s[0].R
x2 := s[0].X + s[0].R
y1 := s[0].Y - s[0].R
y2 := s[0].Y + s[0].R
for _, c := range s[1:] {
x1 = math.Min(x1, c.X-c.R)
x2 = math.Max(x2, c.X+c.R)
y1 = math.Min(y1, c.Y-c.R)
y2 = math.Max(y2, c.Y+c.R)
}
return Rect{x1, y1, x2, y2}
}
var nWorkers = 4
func (s CircleSet) UnionArea(ε float64) (min, max float64) {
sort.Sort(s)
stop := make(chan bool)
inside := make(chan Rect)
outside := make(chan Rect)
unknown := make(chan Rect, 5e7) // XXX
for i := 0; i < nWorkers; i++ {
go s.worker(stop, unknown, inside, outside)
}
r := s.Bounds()
max = r.Area()
unknown <- r
for max-min > ε {
select {
case r = <-inside:
min += r.Area()
case r = <-outside:
max -= r.Area()
}
}
close(stop)
return min, max
}
func (s CircleSet) worker(stop <-chan bool, unk chan Rect, in, out chan<- Rect) {
for {
select {
case <-stop:
return
case r := <-unk:
inside, outside := s.CategorizeR(r)
switch {
case inside:
in <- r
case outside:
out <- r
default:
// Split
midX, midY := r.Centre()
unk <- Rect{r.X1, r.Y1, midX, midY}
unk <- Rect{midX, r.Y1, r.X2, midY}
unk <- Rect{r.X1, midY, midX, r.Y2}
unk <- Rect{midX, midY, r.X2, r.Y2}
}
}
}
}
func (s CircleSet) CategorizeR(r Rect) (inside, outside bool) {
anyCorner := false
for _, c := range s {
full, corner := c.ContainsR(r)
if full {
return true, false // inside
}
anyCorner = anyCorner || corner
}
if anyCorner {
return false, false // uncertain
}
for _, c := range s {
if r.ContainsPC(c) {
return false, false // uncertain
}
}
return false, true // outside
}
func main() {
flag.IntVar(&nWorkers, "workers", nWorkers, "how many worker go routines to use")
maxproc := flag.Int("cpu", runtime.NumCPU(), "GOMAXPROCS setting")
flag.Parse()
if *maxproc > 0 {
runtime.GOMAXPROCS(*maxproc)
} else {
*maxproc = runtime.GOMAXPROCS(0)
}
circles := CircleSet{
NewCircle(1.6417233788, 1.6121789534, 0.0848270516),
NewCircle(-1.4944608174, 1.2077959613, 1.1039549836),
NewCircle(0.6110294452, -0.6907087527, 0.9089162485),
NewCircle(0.3844862411, 0.2923344616, 0.2375743054),
NewCircle(-0.2495892950, -0.3832854473, 1.0845181219),
NewCircle(1.7813504266, 1.6178237031, 0.8162655711),
NewCircle(-0.1985249206, -0.8343333301, 0.0538864941),
NewCircle(-1.7011985145, -0.1263820964, 0.4776976918),
NewCircle(-0.4319462812, 1.4104420482, 0.7886291537),
NewCircle(0.2178372997, -0.9499557344, 0.0357871187),
NewCircle(-0.6294854565, -1.3078893852, 0.7653357688),
NewCircle(1.7952608455, 0.6281269104, 0.2727652452),
NewCircle(1.4168575317, 1.0683357171, 1.1016025378),
NewCircle(1.4637371396, 0.9463877418, 1.1846214562),
NewCircle(-0.5263668798, 1.7315156631, 1.4428514068),
NewCircle(-1.2197352481, 0.9144146579, 1.0727263474),
NewCircle(-0.1389358881, 0.1092805780, 0.7350208828),
NewCircle(1.5293954595, 0.0030278255, 1.2472867347),
NewCircle(-0.5258728625, 1.3782633069, 1.3495508831),
NewCircle(-0.1403562064, 0.2437382535, 1.3804956588),
NewCircle(0.8055826339, -0.0482092025, 0.3327165165),
NewCircle(-0.6311979224, 0.7184578971, 0.2491045282),
NewCircle(1.4685857879, -0.8347049536, 1.3670667538),
NewCircle(-0.6855727502, 1.6465021616, 1.0593087096),
NewCircle(0.0152957411, 0.0638919221, 0.9771215985),
}
fmt.Println("Starting with", len(circles), "circles.")
circles.RemoveContainedC()
fmt.Println("Removing redundant ones leaves", len(circles), "circles.")
fmt.Println("Using", nWorkers, "workers with maxprocs =", *maxproc)
const ε = 0.0001
min, max := circles.UnionArea(ε)
avg := (min + max) / 2.0
rng := max - min
fmt.Printf("Area = %v±%v\n", avg, rng)
fmt.Printf("Area ≈ %.*f\n", 5, avg)
}

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data Circle = Circle { cx :: Double, cy :: Double, cr :: Double }
isInside :: Double -> Double -> Circle -> Bool
isInside x y c = (x - cx c) ^ 2 + (y - cy c) ^ 2 <= (cr c ^ 2)
isInsideAny :: Double -> Double -> [Circle] -> Bool
isInsideAny x y = any (isInside x y)
approximatedArea :: [Circle] -> Int -> Double
approximatedArea cs box_side = (fromIntegral count) * dx * dy
where
-- compute the bounding box of the circles
x_min = minimum [cx c - cr c | c <- circles]
x_max = maximum [cx c + cr c | c <- circles]
y_min = minimum [cy c - cr c | c <- circles]
y_max = maximum [cy c + cr c | c <- circles]
dx = (x_max - x_min) / (fromIntegral box_side)
dy = (y_max - y_min) / (fromIntegral box_side)
count = length [0 | r <- [0 .. box_side - 1],
c <- [0 .. box_side - 1],
isInsideAny (posx c) (posy r) circles]
posy r = y_min + (fromIntegral r) * dy
posx c = x_min + (fromIntegral c) * dx
circles :: [Circle]
circles = [Circle ( 1.6417233788) ( 1.6121789534) 0.0848270516,
Circle (-1.4944608174) ( 1.2077959613) 1.1039549836,
Circle ( 0.6110294452) (-0.6907087527) 0.9089162485,
Circle ( 0.3844862411) ( 0.2923344616) 0.2375743054,
Circle (-0.2495892950) (-0.3832854473) 1.0845181219,
Circle ( 1.7813504266) ( 1.6178237031) 0.8162655711,
Circle (-0.1985249206) (-0.8343333301) 0.0538864941,
Circle (-1.7011985145) (-0.1263820964) 0.4776976918,
Circle (-0.4319462812) ( 1.4104420482) 0.7886291537,
Circle ( 0.2178372997) (-0.9499557344) 0.0357871187,
Circle (-0.6294854565) (-1.3078893852) 0.7653357688,
Circle ( 1.7952608455) ( 0.6281269104) 0.2727652452,
Circle ( 1.4168575317) ( 1.0683357171) 1.1016025378,
Circle ( 1.4637371396) ( 0.9463877418) 1.1846214562,
Circle (-0.5263668798) ( 1.7315156631) 1.4428514068,
Circle (-1.2197352481) ( 0.9144146579) 1.0727263474,
Circle (-0.1389358881) ( 0.1092805780) 0.7350208828,
Circle ( 1.5293954595) ( 0.0030278255) 1.2472867347,
Circle (-0.5258728625) ( 1.3782633069) 1.3495508831,
Circle (-0.1403562064) ( 0.2437382535) 1.3804956588,
Circle ( 0.8055826339) (-0.0482092025) 0.3327165165,
Circle (-0.6311979224) ( 0.7184578971) 0.2491045282,
Circle ( 1.4685857879) (-0.8347049536) 1.3670667538,
Circle (-0.6855727502) ( 1.6465021616) 1.0593087096,
Circle ( 0.0152957411) ( 0.0638919221) 0.9771215985]
main = putStrLn $ "Approximated area: " ++
(show $ approximatedArea circles 5000)

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@ -0,0 +1,169 @@
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
import Data.List (sort)
data Vec = Vec Double Double
vCross, vDot :: Vec -> Vec -> Double
vCross (Vec a b) (Vec c d) = a*d - b*c
vDot (Vec a b) (Vec c d) = a*c + b*d
vAdd, vSub :: Vec -> Vec -> Vec
vAdd (Vec a b) (Vec c d) = Vec (a + c) (b + d)
vSub (Vec a b) (Vec c d) = Vec (a - c) (b - d)
vLen :: Vec -> Double
vLen x = sqrt $ vDot x x
vDist :: Vec -> Vec -> Double
vDist a b = vLen (a `vSub` b)
vScale :: Double -> Vec -> Vec
vScale s (Vec x y) = Vec (x * s) (y * s)
vNorm :: Vec -> Vec
vNorm v@(Vec x y) = Vec (x / l) (y / l) where l = vLen v
newtype Angle = A Double
deriving (Eq, Ord, Num, Fractional)
aPi = A pi
vAngle :: Vec -> Angle
vAngle (Vec x y) = A (atan2 y x)
aNorm :: Angle -> Angle
aNorm a | a > aPi = a - aPi * 2
| a < -aPi = a + aPi * 2
| otherwise = a
data Circle = Circle Double Double Double
deriving (Eq)
circleCross :: Circle -> Circle -> [Angle]
circleCross (Circle x0 y0 r0) (Circle x1 y1 r1)
| d >= r0 + r1 || d <= abs(r0 - r1) = []
| otherwise = map aNorm [ang - da, ang + da]
where
d = vDist (Vec x0 y0) (Vec x1 y1)
s = (r0 + r1 + d) / 2
a = sqrt $ s * (s - d) * (s - r0) * (s - r1)
h = 2 * a / d
dr = Vec (x1 - x0) (y1 - y0)
dx = vScale (sqrt $ r0 ^ 2 - h ^ 2) $ vNorm dr
ang = if r0 ^ 2 + d ^ 2 > r1 ^ 2
then vAngle dr
else aPi + vAngle dr
da = A (asin (h / r0))
-- Angles of the start and end points of the circle arc.
data Angle2 = Angle2 Angle Angle
data Arc = Arc Circle Angle2
arcPoint :: Circle -> Angle -> Vec
arcPoint (Circle x y r) (A a) =
vAdd (Vec x y) (Vec (r * cos a) (r * sin a))
arcStart, arcMid, arcEnd, arcCenter :: Arc -> Vec
arcStart (Arc c (Angle2 a0 a1)) = arcPoint c a0
arcMid (Arc c (Angle2 a0 a1)) = arcPoint c ((a0 + a1) / 2)
arcEnd (Arc c (Angle2 a0 a1)) = arcPoint c a1
arcCenter (Arc (Circle x y r) _) = Vec x y
arcArea :: Arc -> Double
arcArea (Arc (Circle _ _ r) (Angle2 a0 a1)) = r ^ 2 * aDiff / 2
where (A aDiff) = a1 - a0
splitCircles :: [Circle] -> [Arc]
splitCircles cs = filter (not . inAnyCircle) arcs where
cSplit :: (Circle, [Angle]) -> [Arc]
cSplit (c, angs) =
zipWith Arc (repeat c) $ zipWith Angle2 angs $ tail angs
-- If an arc that was part of one circle is inside *another* circle,
-- it will not be part of the zero-winding path, so reject it.
inCircle :: (Vec, Circle) -> Circle -> Bool
inCircle (Vec x0 y0, c1) c2@(Circle x y r) =
c1 /= c2 && vDist (Vec x0 y0) (Vec x y) < r
f :: Circle -> (Circle, [Angle])
f c = (c, sort $ [-aPi, aPi] ++ (concatMap (circleCross c) cs))
cAngs = map f cs
arcs = concatMap cSplit cAngs
inAnyCircle :: Arc -> Bool
inAnyCircle arc@(Arc c _) = any (inCircle (arcMid arc, c)) cs
{-
Given a list of arcs, build sets of closed paths from them.
If one arc's end point is no more than 1e-4 from another's
start point, they are considered connected. Since these
start/end points resulted from intersecting circles earlier,
they *should* be exactly the same, but floating point
precision may cause small differences, hence the 1e-4 error
margin. When there are genuinely different intersections
closer than this margin, the method will backfire, badly.
-}
makePaths :: [Arc] -> [[Arc]]
makePaths arcs = joinArcs [] arcs where
joinArcs :: [Arc] -> [Arc] -> [[Arc]]
joinArcs a [] = [a]
joinArcs [] (x:xs) = joinArcs [x] xs
joinArcs a (x:xs)
| vDist (arcStart (head a)) (arcEnd (last a)) < 1e-4
= a : joinArcs [] (x:xs)
| vDist (arcEnd (last a)) (arcStart x) < 1e-4
= joinArcs (a ++ [x]) xs
| otherwise = joinArcs a (xs ++ [x])
pathArea :: [Arc] -> Double
pathArea arcs = a + polylineArea e where
(a, e) = foldl f (0, []) arcs
f (a, e) arc = (a + arcArea arc, e ++ [arcCenter arc, arcEnd arc])
-- Slice N-polygon into N-2 triangles.
polylineArea :: [Vec] -> Double
polylineArea (v:vs) = sum $ zipWith (triArea v) vs (tail vs)
where triArea a b c = ((b `vSub` a) `vCross` (c `vSub` b)) / 2
circlesArea :: [Circle] -> Double
circlesArea = sum . map pathArea . makePaths . splitCircles
circles :: [Circle]
circles = [Circle ( 1.6417233788) ( 1.6121789534) 0.0848270516,
Circle (-1.4944608174) ( 1.2077959613) 1.1039549836,
Circle ( 0.6110294452) (-0.6907087527) 0.9089162485,
Circle ( 0.3844862411) ( 0.2923344616) 0.2375743054,
Circle (-0.2495892950) (-0.3832854473) 1.0845181219,
Circle ( 1.7813504266) ( 1.6178237031) 0.8162655711,
Circle (-0.1985249206) (-0.8343333301) 0.0538864941,
Circle (-1.7011985145) (-0.1263820964) 0.4776976918,
Circle (-0.4319462812) ( 1.4104420482) 0.7886291537,
Circle ( 0.2178372997) (-0.9499557344) 0.0357871187,
Circle (-0.6294854565) (-1.3078893852) 0.7653357688,
Circle ( 1.7952608455) ( 0.6281269104) 0.2727652452,
Circle ( 1.4168575317) ( 1.0683357171) 1.1016025378,
Circle ( 1.4637371396) ( 0.9463877418) 1.1846214562,
Circle (-0.5263668798) ( 1.7315156631) 1.4428514068,
Circle (-1.2197352481) ( 0.9144146579) 1.0727263474,
Circle (-0.1389358881) ( 0.1092805780) 0.7350208828,
Circle ( 1.5293954595) ( 0.0030278255) 1.2472867347,
Circle (-0.5258728625) ( 1.3782633069) 1.3495508831,
Circle (-0.1403562064) ( 0.2437382535) 1.3804956588,
Circle ( 0.8055826339) (-0.0482092025) 0.3327165165,
Circle (-0.6311979224) ( 0.7184578971) 0.2491045282,
Circle ( 1.4685857879) (-0.8347049536) 1.3670667538,
Circle (-0.6855727502) ( 1.6465021616) 1.0593087096,
Circle ( 0.0152957411) ( 0.0638919221) 0.9771215985]
main = print $ circlesArea circles

View file

@ -0,0 +1,75 @@
NB. check points on a regular grid within the bounding box
N=: 400 NB. grids in each dimension. Controls accuracy.
'X Y R'=: |: XYR=: (_&".;._2~ LF&=)0 :0
1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985
)
bbox=: (<./@:- , >./@:+)&R
BBOXX=: bbox X
BBOXY=: bbox Y
grid=: 3 : 0
'MN MX N'=. y
D=. MX-MN
EDGE=. D%N
(MN(+ -:)EDGE)+(D-EDGE)*(i. % <:)N
)
assert 2.2 2.6 3 3.4 3.8 -: grid 2 4 5
GRIDDED_SAMPLES=: BBOXX {@:;&(grid@:(,&N)) BBOXY
Note '4 4{.GRIDDED_SAMPLES' NB. example
┌─────────────────┬─────────────────┬─────────────────┬─────────────────┐
│_2.59706 _2.20043│_2.59706 _2.19774│_2.59706 _2.19505│_2.59706 _2.19236│
├─────────────────┼─────────────────┼─────────────────┼─────────────────┤
│_2.59434 _2.20043│_2.59434 _2.19774│_2.59434 _2.19505│_2.59434 _2.19236│
├─────────────────┼─────────────────┼─────────────────┼─────────────────┤
│_2.59162 _2.20043│_2.59162 _2.19774│_2.59162 _2.19505│_2.59162 _2.19236│
├─────────────────┼─────────────────┼─────────────────┼─────────────────┤
│_2.58891 _2.20043│_2.58891 _2.19774│_2.58891 _2.19505│_2.58891 _2.19236│
└─────────────────┴─────────────────┴─────────────────┴─────────────────┘
)
XY=: >,GRIDDED_SAMPLES NB. convert to an usual array of floats.
mp=: $:~ :(+/ .*) NB. matrix product
assert (*: 5 13) -: (mp"1) 3 4,:5 12
in=: *:@:{:@:] >: [: mp (- }:) NB. logical function
assert 0 0 in 1 0 2 NB. X Y in X Y R
assert 0 0 (-.@:in) 44 2 3
CONTAINED=: XY in"1/XYR NB. logical table of circles containing each grid
FRACTION=: CONTAINED (+/@:(+./"1)@:[ % *:@:]) N
AREA=: BBOXX*&(-/)BBOXY NB. area of the bounding box.
FRACTION*AREA
NB. result is 21.5645

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@ -0,0 +1,125 @@
public class CirclesTotalArea {
/*
* Rectangles are given as 4-element arrays [tx, ty, w, h].
* Circles are given as 3-element arrays [cx, cy, r].
*/
private static double distSq(double x1, double y1, double x2, double y2) {
return (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);
}
private static boolean rectangleFullyInsideCircle(double[] rect, double[] circ) {
double r2 = circ[2] * circ[2];
// Every corner point of rectangle must be inside the circle.
return distSq(rect[0], rect[1], circ[0], circ[1]) <= r2 &&
distSq(rect[0] + rect[2], rect[1], circ[0], circ[1]) <= r2 &&
distSq(rect[0], rect[1] - rect[3], circ[0], circ[1]) <= r2 &&
distSq(rect[0] + rect[2], rect[1] - rect[3], circ[0], circ[1]) <= r2;
}
private static boolean rectangleSurelyOutsideCircle(double[] rect, double[] circ) {
// Circle center point inside rectangle?
if(rect[0] <= circ[0] && circ[0] <= rect[0] + rect[2] &&
rect[1] - rect[3] <= circ[1] && circ[1] <= rect[1]) { return false; }
// Otherwise, check that each corner is at least (r + Max(w, h)) away from circle center.
double r2 = circ[2] + Math.max(rect[2], rect[3]);
r2 = r2 * r2;
return distSq(rect[0], rect[1], circ[0], circ[1]) >= r2 &&
distSq(rect[0] + rect[2], rect[1], circ[0], circ[1]) >= r2 &&
distSq(rect[0], rect[1] - rect[3], circ[0], circ[1]) >= r2 &&
distSq(rect[0] + rect[2], rect[1] - rect[3], circ[0], circ[1]) >= r2;
}
private static boolean[] surelyOutside;
private static double totalArea(double[] rect, double[][] circs, int d) {
// Check if we can get a quick certain answer.
int surelyOutsideCount = 0;
for(int i = 0; i < circs.length; i++) {
if(rectangleFullyInsideCircle(rect, circs[i])) { return rect[2] * rect[3]; }
if(rectangleSurelyOutsideCircle(rect, circs[i])) {
surelyOutside[i] = true;
surelyOutsideCount++;
}
else { surelyOutside[i] = false; }
}
// Is this rectangle surely outside all circles?
if(surelyOutsideCount == circs.length) { return 0; }
// Are we deep enough in the recursion?
if(d < 1) {
return rect[2] * rect[3] / 3; // Best guess for overlapping portion
}
// Throw out all circles that are surely outside this rectangle.
if(surelyOutsideCount > 0) {
double[][] newCircs = new double[circs.length - surelyOutsideCount][3];
int loc = 0;
for(int i = 0; i < circs.length; i++) {
if(!surelyOutside[i]) { newCircs[loc++] = circs[i]; }
}
circs = newCircs;
}
// Subdivide this rectangle recursively and add up the recursively computed areas.
double w = rect[2] / 2; // New width
double h = rect[3] / 2; // New height
double[][] pieces = {
{ rect[0], rect[1], w, h }, // NW
{ rect[0] + w, rect[1], w, h }, // NE
{ rect[0], rect[1] - h, w, h }, // SW
{ rect[0] + w, rect[1] - h, w, h } // SE
};
double total = 0;
for(double[] piece: pieces) { total += totalArea(piece, circs, d - 1); }
return total;
}
public static double totalArea(double[][] circs, int d) {
double maxx = Double.NEGATIVE_INFINITY;
double minx = Double.POSITIVE_INFINITY;
double maxy = Double.NEGATIVE_INFINITY;
double miny = Double.POSITIVE_INFINITY;
// Find the extremes of x and y for this set of circles.
for(double[] circ: circs) {
if(circ[0] + circ[2] > maxx) { maxx = circ[0] + circ[2]; }
if(circ[0] - circ[2] < minx) { minx = circ[0] - circ[2]; }
if(circ[1] + circ[2] > maxy) { maxy = circ[1] + circ[2]; }
if(circ[1] - circ[2] < miny) { miny = circ[1] - circ[2]; }
}
double[] rect = { minx, maxy, maxx - minx, maxy - miny };
surelyOutside = new boolean[circs.length];
return totalArea(rect, circs, d);
}
public static void main(String[] args) {
double[][] circs = {
{ 1.6417233788, 1.6121789534, 0.0848270516 },
{-1.4944608174, 1.2077959613, 1.1039549836 },
{ 0.6110294452, -0.6907087527, 0.9089162485 },
{ 0.3844862411, 0.2923344616, 0.2375743054 },
{-0.2495892950, -0.3832854473, 1.0845181219 },
{1.7813504266, 1.6178237031, 0.8162655711 },
{-0.1985249206, -0.8343333301, 0.0538864941 },
{-1.7011985145, -0.1263820964, 0.4776976918 },
{-0.4319462812, 1.4104420482, 0.7886291537 },
{0.2178372997, -0.9499557344, 0.0357871187 },
{-0.6294854565, -1.3078893852, 0.7653357688 },
{1.7952608455, 0.6281269104, 0.2727652452 },
{1.4168575317, 1.0683357171, 1.1016025378 },
{1.4637371396, 0.9463877418, 1.1846214562 },
{-0.5263668798, 1.7315156631, 1.4428514068 },
{-1.2197352481, 0.9144146579, 1.0727263474 },
{-0.1389358881, 0.1092805780, 0.7350208828 },
{1.5293954595, 0.0030278255, 1.2472867347 },
{-0.5258728625, 1.3782633069, 1.3495508831 },
{-0.1403562064, 0.2437382535, 1.3804956588 },
{0.8055826339, -0.0482092025, 0.3327165165 },
{-0.6311979224, 0.7184578971, 0.2491045282 },
{1.4685857879, -0.8347049536, 1.3670667538 },
{-0.6855727502, 1.6465021616, 1.0593087096 },
{0.0152957411, 0.0638919221, 0.9771215985 }
};
double ans = totalArea(circs, 24);
System.out.println("Approx. area is " + ans);
System.out.println("Error is " + Math.abs(21.56503660 - ans));
}
}

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@ -0,0 +1,81 @@
def Segment($x; $y): {$x, $y};
def Circle($x; $y; $r) : {$x, $y, $r};
def sq: . * .;
def distance($x; $y):
(($x.x - $y.x)|sq) + (($x.y - $y.y)|sq) | sqrt;
# Is the circle $c1 contained within the circle $c2?
def le($c1; $c2):
$c1 | distance(.;$c2) + .r <= $c2.r;
# Input: an array of circles, sorted by radius length.
# Output: the same array but pruned of any circle contained within another.
def winnow:
if length <= 1 then .
else .[0] as $circle
| .[1:] as $rest
| if any( $rest[]; le($circle; .) )
then $rest | winnow
else [$circle] + ($rest | winnow)
end
end;
# Input: an array of Circles
# Output: the area covered by all the circles
# Method: Cavalieri, horizontally
def areaScan(precision):
def segment($c; $y):
( (($c.r|sq) - (($y - $c.y)|sq) ) | sqrt) as $dr
| Segment($c.x - $dr; $c.x + $dr);
(sort_by(.r) | winnow) as $circles
| (map( .y + .r ) + map(.y - .r )) as $ys
| ((($ys | min) / precision)|floor) as $miny
| ((($ys | max) / precision)|ceil ) as $maxy
| reduce range($miny; 1 + $maxy) as $x ({total: 0};
($x * precision) as $y
| .right = - infinite
| ($circles
| map( select( (($y - .y)|length) < .r)) # length computes abs
| map( segment(.; $y)) ) as $segments
| reduce ($segments | sort_by(.x))[] as $p (.;
if $p.y > .right
then .total += $p.y - ([$p.x, .right]|max)
| .right = $p.y
else .
end ) )
| .total * precision ;
# The Task
def circles: [
Circle( 1.6417233788; 1.6121789534; 0.0848270516),
Circle(-1.4944608174; 1.2077959613; 1.1039549836),
Circle( 0.6110294452; -0.6907087527; 0.9089162485),
Circle( 0.3844862411; 0.2923344616; 0.2375743054),
Circle(-0.2495892950; -0.3832854473; 1.0845181219),
Circle( 1.7813504266; 1.6178237031; 0.8162655711),
Circle(-0.1985249206; -0.8343333301; 0.0538864941),
Circle(-1.7011985145; -0.1263820964; 0.4776976918),
Circle(-0.4319462812; 1.4104420482; 0.7886291537),
Circle( 0.2178372997; -0.9499557344; 0.0357871187),
Circle(-0.6294854565; -1.3078893852; 0.7653357688),
Circle( 1.7952608455; 0.6281269104; 0.2727652452),
Circle( 1.4168575317; 1.0683357171; 1.1016025378),
Circle( 1.4637371396; 0.9463877418; 1.1846214562),
Circle(-0.5263668798; 1.7315156631; 1.4428514068),
Circle(-1.2197352481; 0.9144146579; 1.0727263474),
Circle(-0.1389358881; 0.1092805780; 0.7350208828),
Circle( 1.5293954595; 0.0030278255; 1.2472867347),
Circle(-0.5258728625; 1.3782633069; 1.3495508831),
Circle(-0.1403562064; 0.2437382535; 1.3804956588),
Circle( 0.8055826339; -0.0482092025; 0.3327165165),
Circle(-0.6311979224; 0.7184578971; 0.2491045282),
Circle( 1.4685857879; -0.8347049536; 1.3670667538),
Circle(-0.6855727502; 1.6465021616; 1.0593087096),
Circle( 0.0152957411; 0.0638919221; 0.9771215985)
];
"Approximate area = \(circles | areaScan(1e-5))"

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using Printf
# Total circles area: https://rosettacode.org/wiki/Total_circles_area
xc = [1.6417233788, -1.4944608174, 0.6110294452, 0.3844862411, -0.2495892950, 1.7813504266,
-0.1985249206, -1.7011985145, -0.4319462812, 0.2178372997, -0.6294854565, 1.7952608455,
1.4168575317, 1.4637371396, -0.5263668798, -1.2197352481, -0.1389358881, 1.5293954595,
-0.5258728625, -0.1403562064, 0.8055826339, -0.6311979224, 1.4685857879, -0.6855727502,
0.0152957411]
yc = [1.6121789534, 1.2077959613, -0.6907087527, 0.2923344616, -0.3832854473, 1.6178237031,
-0.8343333301, -0.1263820964, 1.4104420482, -0.9499557344, -1.3078893852, 0.6281269104,
1.0683357171, 0.9463877418, 1.7315156631, 0.9144146579, 0.1092805780, 0.0030278255,
1.3782633069, 0.2437382535, -0.0482092025, 0.7184578971, -0.8347049536, 1.6465021616,
0.0638919221]
r = [0.0848270516, 1.1039549836, 0.9089162485, 0.2375743054, 1.0845181219, 0.8162655711,
0.0538864941, 0.4776976918, 0.7886291537, 0.0357871187, 0.7653357688, 0.2727652452,
1.1016025378, 1.1846214562, 1.4428514068, 1.0727263474, 0.7350208828, 1.2472867347,
1.3495508831, 1.3804956588, 0.3327165165, 0.2491045282, 1.3670667538, 1.0593087096,
0.9771215985]
# Size of my grid -- higher values => higher accuracy.
function main(xc::Vector{<:Real}, yc::Vector{<:Real}, r::Vector{<:Real}, ngrid::Integer=10000)
r2 = r .* r
ncircles = length(xc)
# Compute the bounding box of the circles.
xmin = minimum(xc .- r)
xmax = maximum(xc .+ r)
ymin = minimum(yc .- r)
ymax = maximum(yc .+ r)
# Keep a counter.
inside = 0
# For every point in my grid.
for x in linspace(xmin, xmax, ngrid), y = linspace(ymin, ymax, ngrid)
inside += any(r2 .> (x - xc) .^ 2 + (y - yc) .^ 2)
end
boxarea = (xmax - xmin) * (ymax - ymin)
return boxarea * inside / ngrid ^ 2
end
println(@time main(xc, yc, r, 1000))

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// version 1.1.2
class Circle(val x: Double, val y: Double, val r: Double)
val circles = arrayOf(
Circle( 1.6417233788, 1.6121789534, 0.0848270516),
Circle(-1.4944608174, 1.2077959613, 1.1039549836),
Circle( 0.6110294452, -0.6907087527, 0.9089162485),
Circle( 0.3844862411, 0.2923344616, 0.2375743054),
Circle(-0.2495892950, -0.3832854473, 1.0845181219),
Circle( 1.7813504266, 1.6178237031, 0.8162655711),
Circle(-0.1985249206, -0.8343333301, 0.0538864941),
Circle(-1.7011985145, -0.1263820964, 0.4776976918),
Circle(-0.4319462812, 1.4104420482, 0.7886291537),
Circle( 0.2178372997, -0.9499557344, 0.0357871187),
Circle(-0.6294854565, -1.3078893852, 0.7653357688),
Circle( 1.7952608455, 0.6281269104, 0.2727652452),
Circle( 1.4168575317, 1.0683357171, 1.1016025378),
Circle( 1.4637371396, 0.9463877418, 1.1846214562),
Circle(-0.5263668798, 1.7315156631, 1.4428514068),
Circle(-1.2197352481, 0.9144146579, 1.0727263474),
Circle(-0.1389358881, 0.1092805780, 0.7350208828),
Circle( 1.5293954595, 0.0030278255, 1.2472867347),
Circle(-0.5258728625, 1.3782633069, 1.3495508831),
Circle(-0.1403562064, 0.2437382535, 1.3804956588),
Circle( 0.8055826339, -0.0482092025, 0.3327165165),
Circle(-0.6311979224, 0.7184578971, 0.2491045282),
Circle( 1.4685857879, -0.8347049536, 1.3670667538),
Circle(-0.6855727502, 1.6465021616, 1.0593087096),
Circle( 0.0152957411, 0.0638919221, 0.9771215985)
)
fun Double.sq() = this * this
fun main(args: Array<String>) {
val xMin = circles.map { it.x - it.r }.min()!!
val xMax = circles.map { it.x + it.r }.max()!!
val yMin = circles.map { it.y - it.r }.min()!!
val yMax = circles.map { it.y + it.r }.max()!!
val boxSide = 5000
val dx = (xMax - xMin) / boxSide
val dy = (yMax - yMin) / boxSide
var count = 0
for (r in 0 until boxSide) {
val y = yMin + r * dy
for (c in 0 until boxSide) {
val x = xMin + c * dx
val b = circles.any { (x - it.x).sq() + (y - it.y).sq() <= it.r.sq() }
if (b) count++
}
}
println("Approximate area = ${count * dx * dy}")
}

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// version 1.1.2
class Point(val x: Double, val y: Double)
class Circle(val x: Double, val y: Double, val r: Double)
val circles = arrayOf(
Circle( 1.6417233788, 1.6121789534, 0.0848270516),
Circle(-1.4944608174, 1.2077959613, 1.1039549836),
Circle( 0.6110294452, -0.6907087527, 0.9089162485),
Circle( 0.3844862411, 0.2923344616, 0.2375743054),
Circle(-0.2495892950, -0.3832854473, 1.0845181219),
Circle( 1.7813504266, 1.6178237031, 0.8162655711),
Circle(-0.1985249206, -0.8343333301, 0.0538864941),
Circle(-1.7011985145, -0.1263820964, 0.4776976918),
Circle(-0.4319462812, 1.4104420482, 0.7886291537),
Circle( 0.2178372997, -0.9499557344, 0.0357871187),
Circle(-0.6294854565, -1.3078893852, 0.7653357688),
Circle( 1.7952608455, 0.6281269104, 0.2727652452),
Circle( 1.4168575317, 1.0683357171, 1.1016025378),
Circle( 1.4637371396, 0.9463877418, 1.1846214562),
Circle(-0.5263668798, 1.7315156631, 1.4428514068),
Circle(-1.2197352481, 0.9144146579, 1.0727263474),
Circle(-0.1389358881, 0.1092805780, 0.7350208828),
Circle( 1.5293954595, 0.0030278255, 1.2472867347),
Circle(-0.5258728625, 1.3782633069, 1.3495508831),
Circle(-0.1403562064, 0.2437382535, 1.3804956588),
Circle( 0.8055826339, -0.0482092025, 0.3327165165),
Circle(-0.6311979224, 0.7184578971, 0.2491045282),
Circle( 1.4685857879, -0.8347049536, 1.3670667538),
Circle(-0.6855727502, 1.6465021616, 1.0593087096),
Circle( 0.0152957411, 0.0638919221, 0.9771215985)
)
fun Double.sq() = this * this
fun areaScan(precision: Double): Double {
fun sect(c: Circle, y: Double): Point {
val dr = Math.sqrt(c.r.sq() - (y - c.y).sq())
return Point(c.x - dr, c.x + dr)
}
val ys = circles.map { it.y + it.r } + circles.map { it.y - it.r }
val mins = Math.floor(ys.min()!! / precision).toInt()
val maxs = Math.ceil(ys.max()!! / precision).toInt()
var total = 0.0
for (x in mins..maxs) {
val y = x * precision
var right = Double.NEGATIVE_INFINITY
val points = circles.filter { Math.abs(y - it.y) < it.r }
.map { sect(it, y) }
.sortedBy { it.x }
for (p in points) {
if (p.y <= right) continue
total += p.y - maxOf(p.x, right)
right = p.y
}
}
return total * precision
}
fun main(args: Array<String>) {
val p = 1e-6
println("Approximate area = ${areaScan(p)}")
}

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function res = circles()
tic
%
% Size of my grid -- higher values => higher accuracy.
%
ngrid = 5000;
xc = [1.6417233788 -1.4944608174 0.6110294452 0.3844862411 -0.2495892950 1.7813504266 -0.1985249206 -1.7011985145 -0.4319462812 0.2178372997 -0.6294854565 1.7952608455 1.4168575317 1.4637371396 -0.5263668798 -1.2197352481 -0.1389358881 1.5293954595 -0.5258728625 -0.1403562064 0.8055826339 -0.6311979224 1.4685857879 -0.6855727502 0.0152957411];
yc = [1.6121789534 1.2077959613 -0.6907087527 0.2923344616 -0.3832854473 1.6178237031 -0.8343333301 -0.1263820964 1.4104420482 -0.9499557344 -1.3078893852 0.6281269104 1.0683357171 0.9463877418 1.7315156631 0.9144146579 0.1092805780 0.0030278255 1.3782633069 0.2437382535 -0.0482092025 0.7184578971 -0.8347049536 1.6465021616 0.0638919221];
r = [0.0848270516 1.1039549836 0.9089162485 0.2375743054 1.0845181219 0.8162655711 0.0538864941 0.4776976918 0.7886291537 0.0357871187 0.7653357688 0.2727652452 1.1016025378 1.1846214562 1.4428514068 1.0727263474 0.7350208828 1.2472867347 1.3495508831 1.3804956588 0.3327165165 0.2491045282 1.3670667538 1.0593087096 0.9771215985];
r2 = r .* r;
ncircles = length(xc);
%
% Compute the bounding box of the circles.
%
xmin = min(xc-r);
xmax = max(xc+r);
ymin = min(yc-r);
ymax = max(yc+r);
%
% Keep a counter.
%
inside = 0;
%
% For every point in my grid.
%
for x = linspace(xmin,xmax,ngrid)
for y = linspace(ymin,ymax,ngrid)
if any(r2 > (x - xc).^2 + (y - yc).^2)
inside = inside + 1;
end
end
end
box_area = (xmax-xmin) * (ymax-ymin);
res = box_area * inside / ngrid^2;
toc
end

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data = ImportString[" 1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985", "Table"];
toDisk[{x_, y_, r_}] := Disk[{x, y}, r];
RegionMeasure[RegionUnion[toDisk /@ data]]

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toDisk[{x_, y_, r_}] := Disk[{Rationalize[x, 0], Rationalize[y, 0]}, Rationalize[r, 0]]

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import sequtils
type Circle = tuple[x, y, r: float]
const circles: seq[Circle] = @[
( 1.6417233788, 1.6121789534, 0.0848270516),
(-1.4944608174, 1.2077959613, 1.1039549836),
( 0.6110294452, -0.6907087527, 0.9089162485),
( 0.3844862411, 0.2923344616, 0.2375743054),
(-0.2495892950, -0.3832854473, 1.0845181219),
( 1.7813504266, 1.6178237031, 0.8162655711),
(-0.1985249206, -0.8343333301, 0.0538864941),
(-1.7011985145, -0.1263820964, 0.4776976918),
(-0.4319462812, 1.4104420482, 0.7886291537),
( 0.2178372997, -0.9499557344, 0.0357871187),
(-0.6294854565, -1.3078893852, 0.7653357688),
( 1.7952608455, 0.6281269104, 0.2727652452),
( 1.4168575317, 1.0683357171, 1.1016025378),
( 1.4637371396, 0.9463877418, 1.1846214562),
(-0.5263668798, 1.7315156631, 1.4428514068),
(-1.2197352481, 0.9144146579, 1.0727263474),
(-0.1389358881, 0.1092805780, 0.7350208828),
( 1.5293954595, 0.0030278255, 1.2472867347),
(-0.5258728625, 1.3782633069, 1.3495508831),
(-0.1403562064, 0.2437382535, 1.3804956588),
( 0.8055826339, -0.0482092025, 0.3327165165),
(-0.6311979224, 0.7184578971, 0.2491045282),
( 1.4685857879, -0.8347049536, 1.3670667538),
(-0.6855727502, 1.6465021616, 1.0593087096),
( 0.0152957411, 0.0638919221, 0.9771215985)]
template sqr(x: SomeNumber): SomeNumber = x * x
let xMin = min circles.mapIt(it.x - it.r)
let xMax = max circles.mapIt(it.x + it.r)
let yMin = min circles.mapIt(it.y - it.r)
let yMax = max circles.mapIt(it.y + it.r)
const boxSide = 500
let dx = (xMax - xMin) / boxSide
let dy = (yMax - yMin) / boxSide
var count = 0
for r in 0 ..< boxSide:
let y = yMin + float(r) * dy
for c in 0 ..< boxSide:
let x = xMin + float(c) * dx
for circle in circles:
if sqr(x - circle.x) + sqr(y - circle.y) <= sqr(circle.r):
inc count
break
echo "Approximated area: ", float(count) * dx * dy

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use strict;
use warnings;
use feature 'say';
use List::AllUtils <min max>;
my @circles = (
[ 1.6417233788, 1.6121789534, 0.0848270516],
[-1.4944608174, 1.2077959613, 1.1039549836],
[ 0.6110294452, -0.6907087527, 0.9089162485],
[ 0.3844862411, 0.2923344616, 0.2375743054],
[-0.2495892950, -0.3832854473, 1.0845181219],
[ 1.7813504266, 1.6178237031, 0.8162655711],
[-0.1985249206, -0.8343333301, 0.0538864941],
[-1.7011985145, -0.1263820964, 0.4776976918],
[-0.4319462812, 1.4104420482, 0.7886291537],
[ 0.2178372997, -0.9499557344, 0.0357871187],
[-0.6294854565, -1.3078893852, 0.7653357688],
[ 1.7952608455, 0.6281269104, 0.2727652452],
[ 1.4168575317, 1.0683357171, 1.1016025378],
[ 1.4637371396, 0.9463877418, 1.1846214562],
[-0.5263668798, 1.7315156631, 1.4428514068],
[-1.2197352481, 0.9144146579, 1.0727263474],
[-0.1389358881, 0.1092805780, 0.7350208828],
[ 1.5293954595, 0.0030278255, 1.2472867347],
[-0.5258728625, 1.3782633069, 1.3495508831],
[-0.1403562064, 0.2437382535, 1.3804956588],
[ 0.8055826339, -0.0482092025, 0.3327165165],
[-0.6311979224, 0.7184578971, 0.2491045282],
[ 1.4685857879, -0.8347049536, 1.3670667538],
[-0.6855727502, 1.6465021616, 1.0593087096],
[ 0.0152957411, 0.0638919221, 0.9771215985],
);
my $x_min = min map { $_->[0] - $_->[2] } @circles;
my $x_max = max map { $_->[0] + $_->[2] } @circles;
my $y_min = min map { $_->[1] - $_->[2] } @circles;
my $y_max = max map { $_->[1] + $_->[2] } @circles;
my $box_side = 500;
my $dx = ($x_max - $x_min) / $box_side;
my $dy = ($y_max - $y_min) / $box_side;
my $count = 0;
for my $r (0..$box_side) {
my $y = $y_min + $r * $dy;
for my $c (0..$box_side) {
my $x = $x_min + $c * $dx;
for my $c (@circles) {
$count++ and last if ($x - $$c[0])**2 + ($y - $$c[1])**2 <= $$c[2]**2
}
}
}
printf "Approximated area: %.9f\n", $count * $dx * $dy;

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(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">constant</span> <span style="color: #000000;">circles</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{{</span> <span style="color: #000000;">1.6417233788</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.6121789534</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.0848270516</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">1.4944608174</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.2077959613</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.1039549836</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">0.6110294452</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.6907087527</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.9089162485</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">0.3844862411</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.2923344616</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.2375743054</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.2495892950</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.3832854473</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.0845181219</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.7813504266</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.6178237031</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.8162655711</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.1985249206</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.8343333301</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.0538864941</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">1.7011985145</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.1263820964</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.4776976918</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.4319462812</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.4104420482</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.7886291537</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">0.2178372997</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.9499557344</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.0357871187</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.6294854565</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">1.3078893852</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.7653357688</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.7952608455</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.6281269104</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.2727652452</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.4168575317</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.0683357171</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.1016025378</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.4637371396</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.9463877418</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.1846214562</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.5263668798</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.7315156631</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.4428514068</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">1.2197352481</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.9144146579</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.0727263474</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.1389358881</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.1092805780</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.7350208828</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.5293954595</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.0030278255</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.2472867347</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.5258728625</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.3782633069</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.3495508831</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.1403562064</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.2437382535</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.3804956588</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">0.8055826339</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.0482092025</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.3327165165</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.6311979224</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.7184578971</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.2491045282</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">1.4685857879</span><span style="color: #0000FF;">,</span> <span style="color: #0000FF;">-</span><span style="color: #000000;">0.8347049536</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.3670667538</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{-</span><span style="color: #000000;">0.6855727502</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.6465021616</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">1.0593087096</span><span style="color: #0000FF;">},</span>
<span style="color: #0000FF;">{</span> <span style="color: #000000;">0.0152957411</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.0638919221</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">0.9771215985</span><span style="color: #0000FF;">}},</span>
<span style="color: #0000FF;">{</span><span style="color: #000000;">x</span><span style="color: #0000FF;">,</span><span style="color: #000000;">y</span><span style="color: #0000FF;">,</span><span style="color: #000000;">r</span><span style="color: #0000FF;">}</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">columnize</span><span style="color: #0000FF;">(</span><span style="color: #000000;">circles</span><span style="color: #0000FF;">),</span>
<span style="color: #000000;">r2</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sq_power</span><span style="color: #0000FF;">(</span><span style="color: #000000;">r</span><span style="color: #0000FF;">,</span><span style="color: #000000;">2</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">xMin</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">x</span><span style="color: #0000FF;">,</span><span style="color: #000000;">r</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">xMax</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">x</span><span style="color: #0000FF;">,</span><span style="color: #000000;">r</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">yMin</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">y</span><span style="color: #0000FF;">,</span><span style="color: #000000;">r</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">yMax</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">max</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_add</span><span style="color: #0000FF;">(</span><span style="color: #000000;">y</span><span style="color: #0000FF;">,</span><span style="color: #000000;">r</span><span style="color: #0000FF;">)),</span>
<span style="color: #000000;">boxSide</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">500</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">dx</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">xMax</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">xMin</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">/</span> <span style="color: #000000;">boxSide</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">dy</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">yMax</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">yMin</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">/</span> <span style="color: #000000;">boxSide</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">count</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">cxs</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">boxSide</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">py</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">yMin</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">s</span> <span style="color: #0000FF;">*</span> <span style="color: #000000;">dy</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">cy</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">sq_power</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">py</span><span style="color: #0000FF;">,</span><span style="color: #000000;">y</span><span style="color: #0000FF;">),</span><span style="color: #000000;">2</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">boxSide</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">then</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">px</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">xMin</span> <span style="color: #0000FF;">+</span> <span style="color: #000000;">c</span> <span style="color: #0000FF;">*</span> <span style="color: #000000;">dx</span>
<span style="color: #000000;">cxs</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">cxs</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">sq_power</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">sq_sub</span><span style="color: #0000FF;">(</span><span style="color: #000000;">px</span><span style="color: #0000FF;">,</span><span style="color: #000000;">x</span><span style="color: #0000FF;">),</span><span style="color: #000000;">2</span><span style="color: #0000FF;">))</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">cx</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">cxs</span><span style="color: #0000FF;">[</span><span style="color: #000000;">c</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">circles</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">cx</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]+</span><span style="color: #000000;">cy</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]<=</span><span style="color: #000000;">r2</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span> <span style="color: #000000;">count</span><span style="color: #0000FF;">+=</span><span style="color: #000000;">1</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"Approximate area = %.9f\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">count</span> <span style="color: #0000FF;">*</span> <span style="color: #000000;">dx</span> <span style="color: #0000FF;">*</span> <span style="color: #000000;">dy</span><span style="color: #0000FF;">})</span>
<!--

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from collections import namedtuple
Circle = namedtuple("Circle", "x y r")
circles = [
Circle( 1.6417233788, 1.6121789534, 0.0848270516),
Circle(-1.4944608174, 1.2077959613, 1.1039549836),
Circle( 0.6110294452, -0.6907087527, 0.9089162485),
Circle( 0.3844862411, 0.2923344616, 0.2375743054),
Circle(-0.2495892950, -0.3832854473, 1.0845181219),
Circle( 1.7813504266, 1.6178237031, 0.8162655711),
Circle(-0.1985249206, -0.8343333301, 0.0538864941),
Circle(-1.7011985145, -0.1263820964, 0.4776976918),
Circle(-0.4319462812, 1.4104420482, 0.7886291537),
Circle( 0.2178372997, -0.9499557344, 0.0357871187),
Circle(-0.6294854565, -1.3078893852, 0.7653357688),
Circle( 1.7952608455, 0.6281269104, 0.2727652452),
Circle( 1.4168575317, 1.0683357171, 1.1016025378),
Circle( 1.4637371396, 0.9463877418, 1.1846214562),
Circle(-0.5263668798, 1.7315156631, 1.4428514068),
Circle(-1.2197352481, 0.9144146579, 1.0727263474),
Circle(-0.1389358881, 0.1092805780, 0.7350208828),
Circle( 1.5293954595, 0.0030278255, 1.2472867347),
Circle(-0.5258728625, 1.3782633069, 1.3495508831),
Circle(-0.1403562064, 0.2437382535, 1.3804956588),
Circle( 0.8055826339, -0.0482092025, 0.3327165165),
Circle(-0.6311979224, 0.7184578971, 0.2491045282),
Circle( 1.4685857879, -0.8347049536, 1.3670667538),
Circle(-0.6855727502, 1.6465021616, 1.0593087096),
Circle( 0.0152957411, 0.0638919221, 0.9771215985)]
def main():
# compute the bounding box of the circles
x_min = min(c.x - c.r for c in circles)
x_max = max(c.x + c.r for c in circles)
y_min = min(c.y - c.r for c in circles)
y_max = max(c.y + c.r for c in circles)
box_side = 500
dx = (x_max - x_min) / box_side
dy = (y_max - y_min) / box_side
count = 0
for r in xrange(box_side):
y = y_min + r * dy
for c in xrange(box_side):
x = x_min + c * dx
if any((x-circle.x)**2 + (y-circle.y)**2 <= (circle.r ** 2)
for circle in circles):
count += 1
print "Approximated area:", count * dx * dy
main()

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from math import floor, ceil, sqrt
def area_scan(prec, circs):
def sect((cx, cy, r), y):
dr = sqrt(r ** 2 - (y - cy) ** 2)
return (cx - dr, cx + dr)
ys = [a[1] + a[2] for a in circs] + [a[1] - a[2] for a in circs]
mins = int(floor(min(ys) / prec))
maxs = int(ceil(max(ys) / prec))
total = 0
for y in (prec * x for x in xrange(mins, maxs + 1)):
right = -float("inf")
for (x0, x1) in sorted(sect((cx, cy, r), y)
for (cx, cy, r) in circs
if abs(y - cr) < r):
if x1 <= right:
continue
total += x1 - max(x0, right)
right = x1
return total * prec
def main():
circles = [
( 1.6417233788, 1.6121789534, 0.0848270516),
(-1.4944608174, 1.2077959613, 1.1039549836),
( 0.6110294452, -0.6907087527, 0.9089162485),
( 0.3844862411, 0.2923344616, 0.2375743054),
(-0.2495892950, -0.3832854473, 1.0845181219),
( 1.7813504266, 1.6178237031, 0.8162655711),
(-0.1985249206, -0.8343333301, 0.0538864941),
(-1.7011985145, -0.1263820964, 0.4776976918),
(-0.4319462812, 1.4104420482, 0.7886291537),
( 0.2178372997, -0.9499557344, 0.0357871187),
(-0.6294854565, -1.3078893852, 0.7653357688),
( 1.7952608455, 0.6281269104, 0.2727652452),
( 1.4168575317, 1.0683357171, 1.1016025378),
( 1.4637371396, 0.9463877418, 1.1846214562),
(-0.5263668798, 1.7315156631, 1.4428514068),
(-1.2197352481, 0.9144146579, 1.0727263474),
(-0.1389358881, 0.1092805780, 0.7350208828),
( 1.5293954595, 0.0030278255, 1.2472867347),
(-0.5258728625, 1.3782633069, 1.3495508831),
(-0.1403562064, 0.2437382535, 1.3804956588),
( 0.8055826339, -0.0482092025, 0.3327165165),
(-0.6311979224, 0.7184578971, 0.2491045282),
( 1.4685857879, -0.8347049536, 1.3670667538),
(-0.6855727502, 1.6465021616, 1.0593087096),
( 0.0152957411, 0.0638919221, 0.9771215985)]
p = 1e-3
print "@stepsize", p, "area = %.4f" % area_scan(p, circles)
main()

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from __future__ import division
from math import sqrt
from itertools import count
from pprint import pprint as pp
try:
from itertools import izip as zip
except:
pass
# Remove duplicates and sort, largest first.
circles = sorted(set([
# xcenter ycenter radius
(1.6417233788, 1.6121789534, 0.0848270516),
(-1.4944608174, 1.2077959613, 1.1039549836),
(0.6110294452, -0.6907087527, 0.9089162485),
(0.3844862411, 0.2923344616, 0.2375743054),
(-0.2495892950, -0.3832854473, 1.0845181219),
(1.7813504266, 1.6178237031, 0.8162655711),
(-0.1985249206, -0.8343333301, 0.0538864941),
(-1.7011985145, -0.1263820964, 0.4776976918),
(-0.4319462812, 1.4104420482, 0.7886291537),
(0.2178372997, -0.9499557344, 0.0357871187),
(-0.6294854565, -1.3078893852, 0.7653357688),
(1.7952608455, 0.6281269104, 0.2727652452),
(1.4168575317, 1.0683357171, 1.1016025378),
(1.4637371396, 0.9463877418, 1.1846214562),
(-0.5263668798, 1.7315156631, 1.4428514068),
(-1.2197352481, 0.9144146579, 1.0727263474),
(-0.1389358881, 0.1092805780, 0.7350208828),
(1.5293954595, 0.0030278255, 1.2472867347),
(-0.5258728625, 1.3782633069, 1.3495508831),
(-0.1403562064, 0.2437382535, 1.3804956588),
(0.8055826339, -0.0482092025, 0.3327165165),
(-0.6311979224, 0.7184578971, 0.2491045282),
(1.4685857879, -0.8347049536, 1.3670667538),
(-0.6855727502, 1.6465021616, 1.0593087096),
(0.0152957411, 0.0638919221, 0.9771215985),
]), key=lambda x: -x[-1])
def vdcgen(base=2):
'Van der Corput sequence generator'
for n in count():
vdc, denom = 0,1
while n:
denom *= base
n, remainder = divmod(n, base)
vdc += remainder / denom
yield vdc
def vdc_2d():
'Two dimensional Van der Corput sequence generator'
for x, y in zip(vdcgen(base=2), vdcgen(base=3)):
yield x, y
def bounding_box(circles):
'Return minx, maxx, miny, maxy'
return (min(x - r for x,y,r in circles),
max(x + r for x,y,r in circles),
min(y - r for x,y,r in circles),
max(y + r for x,y,r in circles)
)
def circle_is_in_circle(c1, c2):
x1, y1, r1 = c1
x2, y2, r2 = c2
return sqrt((x2 - x1)**2 + (y2 - y1)**2) <= r1 - r2
def remove_covered_circles(circles):
'Takes circles in decreasing radius order. Removes those covered by others'
covered = []
for i, c1 in enumerate(circles):
eliminate = [c2 for c2 in circles[i+1:]
if circle_is_in_circle(c1, c2)]
if eliminate: covered += [c1, eliminate]
for c in eliminate: circles.remove(c)
#pp(covered)
def main(circles):
print('Originally %i circles' % len(circles))
print('Bounding box: %r' % (bounding_box(circles),))
remove_covered_circles(circles)
print(' down to %i due to some being wholly covered by others' % len(circles))
minx, maxx, miny, maxy = bounding_box(circles)
# Shift to 0,0 and compute r**2 once
circles2 = [(x - minx, y - miny, r*r) for x, y, r in circles]
scalex, scaley = abs(maxx - minx), abs(maxy - miny)
pcount, inside, last = 0, 0, ''
for px, py in vdc_2d():
pcount += 1
px *= scalex; py *= scaley
if any((px-cx)**2 + (py-cy)**2 <= cr2 for cx, cy, cr2 in circles2):
inside += 1
if not pcount % 100000:
area = (inside/pcount) * scalex * scaley
print('Points: %8i, Area estimate: %r'
% (pcount, area))
# Hack to check if precision OK
this = '%.4f' % area
if this == last:
break
else:
last = this
print('The value has settled to %s' % this)
if __name__ == '__main__':
main(circles)

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from collections import namedtuple
from functools import partial
from itertools import repeat, imap, izip
from decimal import Decimal, getcontext
# Requires the egg: https://pypi.python.org/pypi/dmath/
from dmath import atan2, asin, sin, cos, pi as piCompute
getcontext().prec = 40 # Set FP precision.
sqrt = Decimal.sqrt
pi = piCompute()
D2 = Decimal(2)
Vec = namedtuple("Vec", "x y")
vcross = lambda (a, b), (c, d): a*d - b*c
vdot = lambda (a, b), (c, d): a*c + b*d
vadd = lambda (a, b), (c, d): Vec(a + c, b + d)
vsub = lambda (a, b), (c, d): Vec(a - c, b - d)
vlen = lambda x: sqrt(vdot(x, x))
vdist = lambda a, b: vlen(vsub(a, b))
vscale = lambda s, (x, y): Vec(x * s, y * s)
def vnorm(v):
l = vlen(v)
return Vec(v.x / l, v.y / l)
vangle = lambda (x, y): atan2(y, x)
def anorm(a):
if a > pi: return a - pi * D2
if a < -pi: return a + pi * D2
return a
Circle = namedtuple("Circle", "x y r")
def circle_cross((x0, y0, r0), (x1, y1, r1)):
d = vdist(Vec(x0, y0), Vec(x1, y1))
if d >= r0 + r1 or d <= abs(r0 - r1):
return []
s = (r0 + r1 + d) / D2
a = sqrt(s * (s - d) * (s - r0) * (s - r1))
h = D2 * a / d
dr = Vec(x1 - x0, y1 - y0)
dx = vscale(sqrt(r0 ** 2 - h ** 2), vnorm(dr))
ang = vangle(dr) if \
r0 ** 2 + d ** 2 > r1 ** 2 \
else pi + vangle(dr)
da = asin(h / r0)
return map(anorm, [ang - da, ang + da])
# Angles of the start and end points of the circle arc.
Angle2 = namedtuple("Angle2", "a1 a2")
Arc = namedtuple("Arc", "c aa")
arcPoint = lambda (x, y, r), a: \
vadd(Vec(x, y), Vec(r * cos(a), r * sin(a)))
arc_start = lambda (c, (a0, a1)): arcPoint(c, a0)
arc_mid = lambda (c, (a0, a1)): arcPoint(c, (a0 + a1) / D2)
arc_end = lambda (c, (a0, a1)): arcPoint(c, a1)
arc_center = lambda ((x, y, r), _): Vec(x, y)
arc_area = lambda ((_0, _1, r), (a0, a1)): r ** 2 * (a1 - a0) / D2
def split_circles(cs):
cSplit = lambda (c, angs): \
imap(Arc, repeat(c), imap(Angle2, angs, angs[1:]))
# If an arc that was part of one circle is inside *another* circle,
# it will not be part of the zero-winding path, so reject it.
in_circle = lambda ((x0, y0), c), (x, y, r): \
c != Circle(x, y, r) and vdist(Vec(x0, y0), Vec(x, y)) < r
def in_any_circle(arc):
return any(in_circle((arc_mid(arc), arc.c), c) for c in cs)
concat_map = lambda f, xs: [y for x in xs for y in f(x)]
f = lambda c: \
(c, sorted([-pi, pi] +
concat_map(partial(circle_cross, c), cs)))
cAngs = map(f, cs)
arcs = concat_map(cSplit, cAngs)
return filter(lambda ar: not in_any_circle(ar), arcs)
# Given a list of arcs, build sets of closed paths from them.
# If one arc's end point is no more than 1e-4 from another's
# start point, they are considered connected. Since these
# start/end points resulted from intersecting circles earlier,
# they *should* be exactly the same, but floating point
# precision may cause small differences, hence the 1e-4 error
# margin. When there are genuinely different intersections
# closer than this margin, the method will backfire, badly.
def make_paths(arcs):
eps = Decimal("0.0001")
def join_arcs(a, xxs):
if not xxs:
return [a]
x, xs = xxs[0], xxs[1:]
if not a:
return join_arcs([x], xs)
if vdist(arc_start(a[0]), arc_end(a[-1])) < eps:
return [a] + join_arcs([], xxs)
if vdist(arc_end(a[-1]), arc_start(x)) < eps:
return join_arcs(a + [x], xs)
return join_arcs(a, xs + [x])
return join_arcs([], arcs)
# Slice N-polygon into N-2 triangles.
def polyline_area(vvs):
tri_area = lambda a, b, c: vcross(vsub(b, a), vsub(c, b)) / D2
v, vs = vvs[0], vvs[1:]
return sum(tri_area(v, v1, v2) for v1, v2 in izip(vs, vs[1:]))
def path_area(arcs):
f = lambda (a, e), arc: \
(a + arc_area(arc), e + [arc_center(arc), arc_end(arc)])
(a, e) = reduce(f, arcs, (0, []))
return a + polyline_area(e)
circles_area = lambda cs: \
sum(imap(path_area, make_paths(split_circles(cs))))
def main():
raw_circles = """\
1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985""".splitlines()
circles = [Circle(*imap(Decimal, row.split()))
for row in raw_circles]
print "Total Area:", circles_area(circles)
main()

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/*REXX program calculates the total area of (possibly overlapping) circles. */
parse arg box dig . /*obtain optional argument from the CL.*/
if box=='' | box==',' then box= 500 /*Not specified? Then use the default.*/
if dig=='' | dig==',' then dig= 12 /* " " " " " " */
numeric digits dig /*have enough decimal digits for points*/
data = ' 1.6417233788 1.6121789534 0.0848270516',
'-1.4944608174 1.2077959613 1.1039549836',
' 0.6110294452 -0.6907087527 0.9089162485',
' 0.3844862411 0.2923344616 0.2375743054',
'-0.2495892950 -0.3832854473 1.0845181219',
' 1.7813504266 1.6178237031 0.8162655711',
'-0.1985249206 -0.8343333301 0.0538864941',
'-1.7011985145 -0.1263820964 0.4776976918',
'-0.4319462812 1.4104420482 0.7886291537',
' 0.2178372997 -0.9499557344 0.0357871187',
'-0.6294854565 -1.3078893852 0.7653357688',
' 1.7952608455 0.6281269104 0.2727652452',
' 1.4168575317 1.0683357171 1.1016025378',
' 1.4637371396 0.9463877418 1.1846214562',
'-0.5263668798 1.7315156631 1.4428514068',
'-1.2197352481 0.9144146579 1.0727263474',
'-0.1389358881 0.1092805780 0.7350208828',
' 1.5293954595 0.0030278255 1.2472867347',
'-0.5258728625 1.3782633069 1.3495508831',
'-0.1403562064 0.2437382535 1.3804956588',
' 0.8055826339 -0.0482092025 0.3327165165',
'-0.6311979224 0.7184578971 0.2491045282',
' 1.4685857879 -0.8347049536 1.3670667538',
'-0.6855727502 1.6465021616 1.0593087096',
' 0.0152957411 0.0638919221 0.9771215985'
circles= words(data) % 3 /* ══x══ ══y══ ══radius══ */
parse var data minX minY . 1 maxX maxY . /*assign minimum & maximum values.*/
do j=1 for circles; _= j * 3 - 2 /*assign some circles with datum. */
@x.j= word(data,_); @y.j= word(data, _ + 1)
@r.j= word(data,_+2); @rr.j= @r.j**2
minX= min(minX, @x.j - @r.j); maxX= max(maxX, @x.j + @r.j)
minY= min(minY, @y.j - @r.j); maxY= max(maxY, @y.j + @r.j)
end /*j*/
dx= (maxX-minX) / box
dy= (maxY-minY) / box
#= 0 /*count of sample points (so far).*/
do row=0 to box; y= minY + row*dy /*process each of the grid rows. */
do col=0 to box; x= minX + col*dx /* " " " " " column.*/
do k=1 for circles /*now process each new circle. */
if (x - @x.k)**2 + (y - @y.k)**2 <= @rr.k then do; #= # + 1; leave; end
end /*k*/
end /*col*/
end /*row*/
/*stick a fork in it, we're done. */
say 'Using ' box " boxes (which have " box**2 ' points) and ' dig " decimal digits,"
say 'the approximate area is: ' # * dx * dy

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/*REXX program calculates the total area of (possibly overlapping) circles. */
parse arg box dig . /*obtain optional argument from the CL.*/
if box=='' | box==',' then box= -500 /*Not specified? Then use the default.*/
if dig=='' | dig==',' then dig= 12 /* " " " " " " */
verbose= box<0; box= abs(box); boxen= box+1 /*set a flag if we're in verbose mode. */
numeric digits dig /*have enough decimal digits for points*/
/* ══════x══════ ══════y══════ ═══radius═══ ══════x══════ ══════y══════ ═══radius═══*/
$=' 1.6417233788 1.6121789534 0.0848270516 -1.4944608174 1.2077959613 1.1039549836',
' 0.6110294452 -0.6907087527 0.9089162485 0.3844862411 0.2923344616 0.2375743054',
'-0.2495892950 -0.3832854473 1.0845181219 1.7813504266 1.6178237031 0.8162655711',
'-0.1985249206 -0.8343333301 0.0538864941 -1.7011985145 -0.1263820964 0.4776976918',
'-0.4319462812 1.4104420482 0.7886291537 0.2178372997 -0.9499557344 0.0357871187',
'-0.6294854565 -1.3078893852 0.7653357688 1.7952608455 0.6281269104 0.2727652452',
' 1.4168575317 1.0683357171 1.1016025378 1.4637371396 0.9463877418 1.1846214562',
'-0.5263668798 1.7315156631 1.4428514068 -1.2197352481 0.9144146579 1.0727263474',
'-0.1389358881 0.1092805780 0.7350208828 1.5293954595 0.0030278255 1.2472867347',
'-0.5258728625 1.3782633069 1.3495508831 -0.1403562064 0.2437382535 1.3804956588',
' 0.8055826339 -0.0482092025 0.3327165165 -0.6311979224 0.7184578971 0.2491045282',
' 1.4685857879 -0.8347049536 1.3670667538 -0.6855727502 1.6465021616 1.0593087096',
' 0.0152957411 0.0638919221 0.9771215985 ' /*define circles with X, Y, and R.*/
circles= words($) % 3 /*figure out how many circles. */
if verbose then say 'There are' circles "circles." /*display the number of circles. */
parse var $ minX minY . 1 maxX maxY . /*assign minimum & maximum values.*/
do j=1 for circles; _= j * 3 - 2 /*assign some circles with datum. */
@x.j= word($, _); @y.j=word($, _ + 1)
@r.j=word($, _ + 2) / 1; @rr.j= @r.j **2
minX= min(minX, @x.j - @r.j); maxX= max(maxX, @x.j + @r.j)
minY= min(minY, @y.j - @r.j); maxY= max(maxY, @y.j + @r.j)
end /*j*/
do m=1 for circles /*sort the circles by their radii.*/
do n=m+1 to circles /* [↓] sort by descending radii.*/
if @r.n>@r.m then parse value @x.n @y.n @r.n @x.m @y.m @r.m with,
@x.m @y.m @r.m @x.n @y.n @r.n
end /*n*/ /* [↑] Is it higher? Then swap.*/
end /*m*/
dx= (maxX-minX) / box; dy= (maxY-minY) / box /*compute the DX and DY values*/
do z=0 for boxen; rowDY.z= z * dy; colDX.z= z * dx
end /*z*/
w= length(circles) /*W: used for aligning output. */
#in= 0 /*#in ◄───fully contained circles.*/
do j=1 for circles /*traipse through all the circles.*/
do k=1 for circles; if k==j | @r.j==0 then iterate /*skip oneself. */
if @y.j+@r.j > @y.k+@r.k | @x.j-@r.j < @x.k-@r.k |, /*is J inside K? */
@y.j-@r.j < @y.k-@r.k | @x.j+@r.j > @x.k+@r.k then iterate
if verbose then say 'Circle ' right(j,w) ' is contained in circle ' right(k,w)
@r.j= 0; #in= #in + 1 /*elide this circle; and bump #in.*/
end /*k*/
end /*j*/ /* [↑] elided overlapping circle.*/
if #in==0 then #in= 'no' /*use gooder English. (humor). */
if verbose then do; say; say #in " circles are fully contained within other circles.";end
nC= 0 /*number of "new" circles. */
do n=1 for circles; if @r.n==0 then iterate /*skip circles with zero radii. */
nC= nC + 1; @x.nC= @x.n; @y.nC= @y.n; @r.nC= @r.n; @rr.nC= @r.n**2
end /*n*/ /* [↑] elide overlapping circles.*/
#= 0 /*count of sample points (so far).*/
do row=0 for boxen; y= minY + rowDY.row /*process each of the grid row. */
do col=0 for boxen; x= minX + colDX.col /* " " " " " column.*/
do k=1 for nC /*now process each new circle. */
if (x - @x.k)**2 + (y - @y.k)**2 <= @rr.k then do; #= # + 1; leave; end
end /*k*/
end /*col*/
end /*row*/
say /*stick a fork in it, we're done. */
say 'Using ' box " boxes (which have " box**2 ' points) and ' dig " decimal digits,"
say 'the approximate area is: ' # * dx * dy

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@ -0,0 +1,177 @@
class Point {
has Real $.x;
has Real $.y;
has Int $!cbits; # bitmap of circle membership
method cbits { $!cbits //= set_cbits(self) }
method gist { $!x ~ "\t" ~ $!y }
}
multi infix:<to>(Point $p1, Point $p2) {
sqrt ($p1.x - $p2.x) ** 2 + ($p1.y - $p2.y) ** 2;
}
multi infix:<mid>(Point $p1, Point $p2) {
Point.new(x => ($p1.x + $p2.x) / 2, y => ($p1.y + $p2.y) / 2);
}
class Circle {
has Point $.center;
has Real $.radius;
has Point $.north = Point.new(x => $!center.x, y => $!center.y + $!radius);
has Point $.west = Point.new(x => $!center.x - $!radius, y => $!center.y);
has Point $.south = Point.new(x => $!center.x, y => $!center.y - $!radius);
has Point $.east = Point.new(x => $!center.x + $!radius, y => $!center.y);
multi method contains(Circle $c) { $!center to $c.center <= $!radius - $c.radius }
multi method contains(Point $p) { $!center to $p <= $!radius }
method gist { $!center.gist ~ "\t" ~ $.radius }
}
class Rect {
has Point $.nw;
has Point $.ne;
has Point $.sw;
has Point $.se;
method diag { $!ne to $!se }
method area { ($!ne.x - $!nw.x) * ($!nw.y - $!sw.y) }
method contains(Point $p) {
$!nw.x < $p.x < $!ne.x and
$!sw.y < $p.y < $!nw.y;
}
}
my @rawcircles = sort -*.radius,
map -> $x, $y, $radius { Circle.new(:center(Point.new(:$x, :$y)), :$radius) },
<
1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985
>».Num;
# remove redundant circles
my @circles;
while @rawcircles {
my $c = @rawcircles.shift;
next if @circles.any.contains($c);
push @circles, $c;
}
sub set_cbits(Point $p) {
my $cbits = 0;
for @circles Z (1,2,4...*) -> ($c, $b) {
$cbits += $b if $c.contains($p);
}
$cbits;
}
my $xmin = min @circles.map: { .center.x - .radius }
my $xmax = max @circles.map: { .center.x + .radius }
my $ymin = min @circles.map: { .center.y - .radius }
my $ymax = max @circles.map: { .center.y + .radius }
my $min-radius = @circles[*-1].radius;
my $outer-rect = Rect.new:
nw => Point.new(x => $xmin, y => $ymax),
ne => Point.new(x => $xmax, y => $ymax),
sw => Point.new(x => $xmin, y => $ymin),
se => Point.new(x => $xmax, y => $ymin);
my $outer-area = $outer-rect.area;
my @unknowns = $outer-rect;
my $known-dry = 0e0;
my $known-wet = 0e0;
my $div = 1;
# divide current rects each into four rects, analyze each
sub divide(@old) {
$div *= 2;
# rects too small to hold circle?
my $smallish = @old[0].diag < $min-radius;
my @unk;
for @old {
my $center = .nw mid .se;
my $north = .nw mid .ne;
my $south = .sw mid .se;
my $west = .nw mid .sw;
my $east = .ne mid .se;
for Rect.new(nw => .nw, ne => $north, sw => $west, se => $center),
Rect.new(nw => $north, ne => .ne, sw => $center, se => $east),
Rect.new(nw => $west, ne => $center, sw => .sw, se => $south),
Rect.new(nw => $center, ne => $east, sw => $south, se => .se)
{
my @bits = .nw.cbits, .ne.cbits, .sw.cbits, .se.cbits;
# if all 4 points wet by same circle, guaranteed wet
if [+&] @bits {
$known-wet += .area;
next;
}
# if all 4 corners are dry, must check further
if not [+|] @bits and $smallish {
# check that no circle bulges into this rect
my $ok = True;
for @circles -> $c {
if .contains($c.east) or .contains($c.west) or
.contains($c.north) or .contains($c.south)
{
$ok = False;
last;
}
}
if $ok {
$known-dry += .area;
next;
}
}
push @unk, $_; # dunno yet
}
}
@unk;
}
my $delta = 0.001;
repeat until my $diff < $delta {
@unknowns = divide(@unknowns);
$diff = $outer-area - $known-dry - $known-wet;
say 'div: ', $div.fmt('%-5d'),
' unk: ', (+@unknowns).fmt('%-6d'),
' est: ', ($known-wet + $diff/2).fmt('%9.6f'),
' wet: ', $known-wet.fmt('%9.6f'),
' dry: ', ($outer-area - $known-dry).fmt('%9.6f'),
' diff: ', $diff.fmt('%9.6f'),
' error: ', ($diff - @unknowns * @unknowns[0].area).fmt('%e');
}

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circles = [
[ 1.6417233788, 1.6121789534, 0.0848270516],
[-1.4944608174, 1.2077959613, 1.1039549836],
[ 0.6110294452, -0.6907087527, 0.9089162485],
[ 0.3844862411, 0.2923344616, 0.2375743054],
[-0.2495892950, -0.3832854473, 1.0845181219],
[ 1.7813504266, 1.6178237031, 0.8162655711],
[-0.1985249206, -0.8343333301, 0.0538864941],
[-1.7011985145, -0.1263820964, 0.4776976918],
[-0.4319462812, 1.4104420482, 0.7886291537],
[ 0.2178372997, -0.9499557344, 0.0357871187],
[-0.6294854565, -1.3078893852, 0.7653357688],
[ 1.7952608455, 0.6281269104, 0.2727652452],
[ 1.4168575317, 1.0683357171, 1.1016025378],
[ 1.4637371396, 0.9463877418, 1.1846214562],
[-0.5263668798, 1.7315156631, 1.4428514068],
[-1.2197352481, 0.9144146579, 1.0727263474],
[-0.1389358881, 0.1092805780, 0.7350208828],
[ 1.5293954595, 0.0030278255, 1.2472867347],
[-0.5258728625, 1.3782633069, 1.3495508831],
[-0.1403562064, 0.2437382535, 1.3804956588],
[ 0.8055826339, -0.0482092025, 0.3327165165],
[-0.6311979224, 0.7184578971, 0.2491045282],
[ 1.4685857879, -0.8347049536, 1.3670667538],
[-0.6855727502, 1.6465021616, 1.0593087096],
[ 0.0152957411, 0.0638919221, 0.9771215985],
]
def minmax_circle(circles)
xmin = circles.map {|xc, yc, radius| xc - radius}.min
xmax = circles.map {|xc, yc, radius| xc + radius}.max
ymin = circles.map {|xc, yc, radius| yc - radius}.min
ymax = circles.map {|xc, yc, radius| yc + radius}.max
[xmin, xmax, ymin, ymax]
end
# remove internal circle
def select_circle(circles)
circles = circles.sort_by{|cx,cy,r| -r}
size = circles.size
select = [*0...size]
for i in 0...size-1
xi,yi,ri = circles[i].to_a
for j in i+1...size
xj,yj,rj = circles[j].to_a
select -= [j] if (xi-xj)**2 + (yi-yj)**2 <= (ri-rj)**2
end
end
circles.values_at(*select)
end
circles = select_circle(circles)

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def grid_sample(circles, box_side=500)
# compute the bounding box of the circles
xmin, xmax, ymin, ymax = minmax_circle(circles)
dx = (xmax - xmin) / box_side
dy = (ymax - ymin) / box_side
circle2 = circles.map{|cx,cy,r| [cx,cy,r*r]}
include = ->(x,y){circle2.any?{|cx, cy, r2| (x-cx)**2 + (y-cy)**2 < r2}}
count = 0
box_side.times do |r|
y = ymin + r * dy
box_side.times do |c|
x = xmin + c * dx
count += 1 if include[x,y]
end
end
#puts box_side => "Approximated area:#{count * dx * dy}"
count * dx * dy
end
puts "Grid Sample"
n = 500
2.times do
t0 = Time.now
puts "Approximated area:#{grid_sample(circles, n)} (#{n} grid)"
n *= 2
puts "#{Time.now - t0} sec"
end

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def area_scan(prec, circles)
sect = ->(y) do
circles.select{|cx,cy,r| (y - cy).abs < r}.map do |cx,cy,r|
dr = Math.sqrt(r ** 2 - (y - cy) ** 2)
[cx - dr, cx + dr]
end
end
xmin, xmax, ymin, ymax = minmax_circle(circles)
ymin = (ymin / prec).floor
ymax = (ymax / prec).ceil
total = 0
for y in ymin..ymax
y *= prec
right = xmin
for x0, x1 in sect[y].sort
next if x1 <= right
total += x1 - [x0, right].max
right = x1
end
end
total * prec
end
puts "Scanline Method"
prec = 1e-2
3.times do
t0 = Time.now
puts "%8.6f : %12.9f, %p sec" % [prec, area_scan(prec, circles), Time.now-t0]
prec /= 10
end

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set circles {
1.6417233788 1.6121789534 0.0848270516
-1.4944608174 1.2077959613 1.1039549836
0.6110294452 -0.6907087527 0.9089162485
0.3844862411 0.2923344616 0.2375743054
-0.2495892950 -0.3832854473 1.0845181219
1.7813504266 1.6178237031 0.8162655711
-0.1985249206 -0.8343333301 0.0538864941
-1.7011985145 -0.1263820964 0.4776976918
-0.4319462812 1.4104420482 0.7886291537
0.2178372997 -0.9499557344 0.0357871187
-0.6294854565 -1.3078893852 0.7653357688
1.7952608455 0.6281269104 0.2727652452
1.4168575317 1.0683357171 1.1016025378
1.4637371396 0.9463877418 1.1846214562
-0.5263668798 1.7315156631 1.4428514068
-1.2197352481 0.9144146579 1.0727263474
-0.1389358881 0.1092805780 0.7350208828
1.5293954595 0.0030278255 1.2472867347
-0.5258728625 1.3782633069 1.3495508831
-0.1403562064 0.2437382535 1.3804956588
0.8055826339 -0.0482092025 0.3327165165
-0.6311979224 0.7184578971 0.2491045282
1.4685857879 -0.8347049536 1.3670667538
-0.6855727502 1.6465021616 1.0593087096
0.0152957411 0.0638919221 0.9771215985
}
proc init {} {
upvar 1 circles circles
set xMin [set yMin inf]
set xMax [set yMax -inf]
set i -1
foreach {xc yc rad} $circles {
set xMin [expr {min($xMin, $xc-$rad)}]
set xMax [expr {max($xMax, $xc+$rad)}]
set yMin [expr {min($yMin, $yc-$rad)}]
set yMax [expr {max($yMax, $yc+$rad)}]
lset circles [incr i 3] [expr {$rad**2}]
}
return [list $xMin $xMax $yMin $yMax]
}
proc sampleGrid {circles steps} {
lassign [init] xMin xMax yMin yMax
set dx [expr {($xMax-$xMin)/$steps}]
set dy [expr {($yMax-$yMin)/$steps}]
set n 0
for {set i 0} {$i < $steps} {incr i} {
set x [expr {$xMin + $i * $dx}]
for {set j 0} {$j < $steps} {incr j} {
set y [expr {$yMin + $j * $dy}]
foreach {xc yc rad2} $circles {
if {($x-$xc)**2 + ($y-$yc)**2 <= $rad2} {
incr n
break
}
}
}
}
return [expr {$dx * $dy * $n}]
}
proc sampleMC {circles samples} {
lassign [init] xMin xMax yMin yMax
set n 0
for {set i 0} {$i < $samples} {incr i} {
set x [expr {$xMin+rand()*($xMax-$xMin)}]
set y [expr {$yMin+rand()*($yMax-$yMin)}]
foreach {xc yc rad2} $circles {
if {($x-$xc)**2 + ($y-$yc)**2 <= $rad2} {
incr n
break
}
}
}
return [expr {($xMax-$xMin) * ($yMax-$yMin) * $n / $samples}]
}
proc samplePerturb {circles steps votes} {
lassign [init] xMin xMax yMin yMax
set dx [expr {($xMax-$xMin)/$steps}]
set dy [expr {($yMax-$yMin)/$steps}]
set n 0
for {set i 0} {$i < $steps} {incr i} {
set x [expr {$xMin + $i * $dx}]
for {set j 0} {$j < $steps} {incr j} {
set y [expr {$yMin + $j * $dy}]
foreach {xc yc rad2} $circles {
set in 0
for {set v 0} {$v < $votes} {incr v} {
set xr [expr {$x + (rand()-0.5)*$dx}]
set yr [expr {$y + (rand()-0.5)*$dy}]
if {($xr-$xc)**2 + ($yr-$yc)**2 <= $rad2} {
incr in
}
}
if {$in*2 >= $votes} {
incr n
break
}
}
}
}
return [expr {$dx * $dy * $n}]
}
puts [format "estimated area (grid): %.4f" [sampleGrid $circles 500]]
puts [format "estimated area (monte carlo): %.2f" [sampleMC $circles 1000000]]
puts [format "estimated area (perturbed sample): %.4f" [samplePerturb $circles 500 5]]

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Public c As Variant
Public pi As Double
Dim arclists() As Variant
Public Enum circles_
xc = 0
yc
rc
End Enum
Public Enum arclists_
rho
x_
y_
i_
End Enum
Public Enum shoelace_axis
u = 0
v
End Enum
Private Sub give_a_list_of_circles()
c = Array(Array(1.6417233788, 1.6121789534, 0.0848270516), _
Array(-1.4944608174, 1.2077959613, 1.1039549836), _
Array(0.6110294452, -0.6907087527, 0.9089162485), _
Array(0.3844862411, 0.2923344616, 0.2375743054), _
Array(-0.249589295, -0.3832854473, 1.0845181219), _
Array(1.7813504266, 1.6178237031, 0.8162655711), _
Array(-0.1985249206, -0.8343333301, 0.0538864941), _
Array(-1.7011985145, -0.1263820964, 0.4776976918), _
Array(-0.4319462812, 1.4104420482, 0.7886291537), _
Array(0.2178372997, -0.9499557344, 0.0357871187), _
Array(-0.6294854565, -1.3078893852, 0.7653357688), _
Array(1.7952608455, 0.6281269104, 0.2727652452), _
Array(1.4168575317, 1.0683357171, 1.1016025378), _
Array(1.4637371396, 0.9463877418, 1.1846214562), _
Array(-0.5263668798, 1.7315156631, 1.4428514068), _
Array(-1.2197352481, 0.9144146579, 1.0727263474), _
Array(-0.1389358881, 0.109280578, 0.7350208828), _
Array(1.5293954595, 0.0030278255, 1.2472867347), _
Array(-0.5258728625, 1.3782633069, 1.3495508831), _
Array(-0.1403562064, 0.2437382535, 1.3804956588), _
Array(0.8055826339, -0.0482092025, 0.3327165165), _
Array(-0.6311979224, 0.7184578971, 0.2491045282), _
Array(1.4685857879, -0.8347049536, 1.3670667538), _
Array(-0.6855727502, 1.6465021616, 1.0593087096), _
Array(0.0152957411, 0.0638919221, 0.9771215985))
pi = WorksheetFunction.pi()
End Sub
Private Function shoelace(s As Collection) As Double
's is a collection of coordinate pairs (x, y),
'in clockwise order for positive result.
'The last pair is identical to the first pair.
'These pairs map a polygonal area.
'The area is computed with the shoelace algoritm.
'see the Rosetta Code task.
Dim t As Double
If s.Count > 2 Then
s.Add s(1)
For i = 1 To s.Count - 1
t = t + s(i + 1)(u) * s(i)(v) - s(i)(u) * s(i + 1)(v)
Next i
End If
shoelace = t / 2
End Function
Private Sub arc_sub(acol As Collection, f0 As Double, u0 As Double, v0 As Double, _
f1 As Double, u1 As Double, v1 As Double, this As Integer, j As Integer)
'subtract the arc from f0 to f1 from the arclist acol
'complicated to deal with edge cases
If acol.Count = 0 Then Exit Sub 'nothing to subtract from
Debug.Assert acol.Count Mod 2 = 0
Debug.Assert f0 <> f1
If f1 = pi Or f1 + pi < 5E-16 Then f1 = -f1
If f0 = pi Or f0 + pi < 5E-16 Then f0 = -f0
If f0 < f1 Then
'the arc does not pass the negative x-axis
'find a such that acol(a)(0)<f0<acol(a+1)(0)
' and b such that acol(b)(0)<f1<acol(b+1)(0)
If f1 < acol(1)(rho) Or f0 > acol(acol.Count)(rho) Then Exit Sub 'nothing to subtract
i = acol.Count + 1
start = 1
Do
i = i - 1
Loop Until f1 > acol(i)(rho)
If i Mod 2 = start Then
acol.Add Array(f1, u1, v1, j), after:=i
End If
i = 0
Do
i = i + 1
Loop Until f0 < acol(i)(rho)
If i Mod 2 = 1 - start Then
acol.Add Array(f0, u0, v0, j), before:=i
i = i + 1
End If
Do While acol(i)(rho) < f1
acol.Remove i
If i > acol.Count Then Exit Do
Loop
Else
start = 1
If f0 > acol(1)(rho) Then
i = acol.Count + 1
Do
i = i - 1
Loop While f0 < acol(i)(0)
If f0 = pi Then
acol.Add Array(f0, u0, v0, j), before:=i
Else
If i Mod 2 = start Then
acol.Add Array(f0, u0, v0, j), after:=i
End If
End If
End If
If f1 <= acol(acol.Count)(rho) Then
i = 0
Do
i = i + 1
Loop While f1 > acol(i)(rho)
If f1 + pi < 5E-16 Then
acol.Add Array(f1, u1, v1, j), after:=i
Else
If i Mod 2 = 1 - start Then
acol.Add Array(f1, u1, v1, j), before:=i
End If
End If
End If
Do While acol(acol.Count)(rho) > f0 Or acol(acol.Count)(i_) = -1
acol.Remove acol.Count
If acol.Count = 0 Then Exit Do
Loop
If acol.Count > 0 Then
Do While acol(1)(rho) < f1 Or (f1 = -pi And acol(1)(i_) = this)
acol.Remove 1
If acol.Count = 0 Then Exit Do
Loop
End If
End If
End Sub
Private Sub circle_cross()
ReDim arclists(LBound(c) To UBound(c))
Dim alpha As Double, beta As Double
Dim x3 As Double, x4 As Double, y3 As Double, y4 As Double
Dim i As Integer, j As Integer
For i = LBound(c) To UBound(c)
Dim arccol As New Collection
'arccol is a collection or surviving arcs of circle i.
'It starts with the full circle. The collection
'alternates between start and ending angles of the arcs.
'This winds counter clockwise.
'Noted are angle, x coordinate, y coordinate and
'index number of circles with which circle i
'intersects at that angle and -1 marks visited. This defines
'ultimately a double linked list. So winding
'clockwise in the end is easy.
arccol.Add Array(-pi, c(i)(xc) - c(i)(r), c(i)(yc), i)
arccol.Add Array(pi, c(i)(xc) - c(i)(r), c(i)(yc), -1)
For j = LBound(c) To UBound(c)
If i <> j Then
x0 = c(i)(xc)
y0 = c(i)(yc)
r0 = c(i)(rc)
x1 = c(j)(xc)
y1 = c(j)(yc)
r1 = c(j)(rc)
d = Sqr((x0 - x1) ^ 2 + (y0 - y1) ^ 2)
'Ignore 0 and 1, we need only the 2 case.
If d >= r0 + r1 Or d <= Abs(r0 - r1) Then
'no intersections
Else
a = (r0 ^ 2 - r1 ^ 2 + d ^ 2) / (2 * d)
h = Sqr(r0 ^ 2 - a ^ 2)
x2 = x0 + a * (x1 - x0) / d
y2 = y0 + a * (y1 - y0) / d
x3 = x2 + h * (y1 - y0) / d
y3 = y2 - h * (x1 - x0) / d
alpha = WorksheetFunction.Atan2(x3 - x0, y3 - y0)
x4 = x2 - h * (y1 - y0) / d
y4 = y2 + h * (x1 - x0) / d
beta = WorksheetFunction.Atan2(x4 - x0, y4 - y0)
'alpha is counterclockwise positioned w.r.t beta
'so the arc from beta to alpha (ccw) has to be
'subtracted from the list of surviving arcs as
'this arc lies fully in circle j
arc_sub arccol, alpha, x3, y3, beta, x4, y4, i, j
End If
End If
Next j
Set arclists(i) = arccol
Set arccol = Nothing
Next i
End Sub
Private Sub make_path()
Dim pathcol As New Collection, arcsum As Double
i0 = UBound(arclists)
finished = False
Do While True
arcsum = 0
Do While arclists(i0).Count = 0
i0 = i0 - 1
Loop
j0 = arclists(i0).Count
next_i = i0
next_j = j0
Do While True
x = arclists(next_i)(next_j)(x_)
y = arclists(next_i)(next_j)(y_)
pathcol.Add Array(x, y)
prev_i = next_i
prev_j = next_j
If arclists(next_i)(next_j - 1)(i_) = next_i Then
'skip the join point at the negative x-axis
next_j = arclists(next_i).Count - 1
If next_j = 1 Then Exit Do 'loose full circle arc
Else
next_j = next_j - 1
End If
'------------------------------
r = c(next_i)(rc)
a1 = arclists(next_i)(prev_j)(rho)
a2 = arclists(next_i)(next_j)(rho)
If a1 > a2 Then
alpha = a1 - a2
Else
alpha = 2 * pi - a2 + a1
End If
arcsum = arcsum + r * r * (alpha - Sin(alpha)) / 2
'------------------------------
next_i = arclists(next_i)(next_j)(i_)
next_j = arclists(next_i).Count
If next_j = 0 Then Exit Do 'skip loose arcs
Do While arclists(next_i)(next_j)(i_) <> prev_i
'find the matching item
next_j = next_j - 1
Loop
If next_i = i0 And next_j = j0 Then
finished = True
Exit Do
End If
Loop
If finished Then Exit Do
i0 = i0 - 1
Set pathcol = Nothing
Loop
Debug.Print shoelace(pathcol) + arcsum
End Sub
Public Sub total_circles()
give_a_list_of_circles
circle_cross
make_path
End Sub

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import "/dynamic" for Tuple
import "/math" for Nums
var Circle = Tuple.create("Circle", ["x", "y", "r"])
var circles = [
Circle.new( 1.6417233788, 1.6121789534, 0.0848270516),
Circle.new(-1.4944608174, 1.2077959613, 1.1039549836),
Circle.new( 0.6110294452, -0.6907087527, 0.9089162485),
Circle.new( 0.3844862411, 0.2923344616, 0.2375743054),
Circle.new(-0.2495892950, -0.3832854473, 1.0845181219),
Circle.new( 1.7813504266, 1.6178237031, 0.8162655711),
Circle.new(-0.1985249206, -0.8343333301, 0.0538864941),
Circle.new(-1.7011985145, -0.1263820964, 0.4776976918),
Circle.new(-0.4319462812, 1.4104420482, 0.7886291537),
Circle.new( 0.2178372997, -0.9499557344, 0.0357871187),
Circle.new(-0.6294854565, -1.3078893852, 0.7653357688),
Circle.new( 1.7952608455, 0.6281269104, 0.2727652452),
Circle.new( 1.4168575317, 1.0683357171, 1.1016025378),
Circle.new( 1.4637371396, 0.9463877418, 1.1846214562),
Circle.new(-0.5263668798, 1.7315156631, 1.4428514068),
Circle.new(-1.2197352481, 0.9144146579, 1.0727263474),
Circle.new(-0.1389358881, 0.1092805780, 0.7350208828),
Circle.new( 1.5293954595, 0.0030278255, 1.2472867347),
Circle.new(-0.5258728625, 1.3782633069, 1.3495508831),
Circle.new(-0.1403562064, 0.2437382535, 1.3804956588),
Circle.new( 0.8055826339, -0.0482092025, 0.3327165165),
Circle.new(-0.6311979224, 0.7184578971, 0.2491045282),
Circle.new( 1.4685857879, -0.8347049536, 1.3670667538),
Circle.new(-0.6855727502, 1.6465021616, 1.0593087096),
Circle.new( 0.0152957411, 0.0638919221, 0.9771215985)
]
var sq = Fn.new { |v| v * v }
var xMin = Nums.min(circles.map { |c| c.x - c.r })
var xMax = Nums.max(circles.map { |c| c.x + c.r })
var yMin = Nums.min(circles.map { |c| c.y - c.r })
var yMax = Nums.max(circles.map { |c| c.y + c.r })
var boxSide = 3000
var dx = (xMax - xMin) / boxSide
var dy = (yMax - yMin) / boxSide
var count = 0
for (r in 0...boxSide) {
var y = yMin + r * dy
for (c in 0...boxSide) {
var x = xMin + c * dx
var b = circles.any { |c| sq.call(x-c.x) + sq.call(y-c.y) <= sq.call(c.r) }
if (b) count = count + 1
}
}
System.print("Approximate area = %(count * dx * dy)")

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import "/dynamic" for Tuple
import "/math" for Nums
import "/sort" for Sort
var Point = Tuple.create("Point", ["x", "y"])
var Circle = Tuple.create("Circle", ["x", "y", "r"])
var circles = [
Circle.new( 1.6417233788, 1.6121789534, 0.0848270516),
Circle.new(-1.4944608174, 1.2077959613, 1.1039549836),
Circle.new( 0.6110294452, -0.6907087527, 0.9089162485),
Circle.new( 0.3844862411, 0.2923344616, 0.2375743054),
Circle.new(-0.2495892950, -0.3832854473, 1.0845181219),
Circle.new( 1.7813504266, 1.6178237031, 0.8162655711),
Circle.new(-0.1985249206, -0.8343333301, 0.0538864941),
Circle.new(-1.7011985145, -0.1263820964, 0.4776976918),
Circle.new(-0.4319462812, 1.4104420482, 0.7886291537),
Circle.new( 0.2178372997, -0.9499557344, 0.0357871187),
Circle.new(-0.6294854565, -1.3078893852, 0.7653357688),
Circle.new( 1.7952608455, 0.6281269104, 0.2727652452),
Circle.new( 1.4168575317, 1.0683357171, 1.1016025378),
Circle.new( 1.4637371396, 0.9463877418, 1.1846214562),
Circle.new(-0.5263668798, 1.7315156631, 1.4428514068),
Circle.new(-1.2197352481, 0.9144146579, 1.0727263474),
Circle.new(-0.1389358881, 0.1092805780, 0.7350208828),
Circle.new( 1.5293954595, 0.0030278255, 1.2472867347),
Circle.new(-0.5258728625, 1.3782633069, 1.3495508831),
Circle.new(-0.1403562064, 0.2437382535, 1.3804956588),
Circle.new( 0.8055826339, -0.0482092025, 0.3327165165),
Circle.new(-0.6311979224, 0.7184578971, 0.2491045282),
Circle.new( 1.4685857879, -0.8347049536, 1.3670667538),
Circle.new(-0.6855727502, 1.6465021616, 1.0593087096),
Circle.new( 0.0152957411, 0.0638919221, 0.9771215985)
]
var sq = Fn.new { |v| v * v }
var areaScan = Fn.new { |precision|
var sect = Fn.new { |c, y|
var dr = (sq.call(c.r) - sq.call(y-c.y)).sqrt
return Point.new(c.x - dr, c.x + dr)
}
var ys = circles.map { |c| c.y + c.r }.toList + circles.map { |c| c.y - c.r }.toList
var mins = (Nums.min(ys)/precision).floor
var maxs = (Nums.max(ys)/precision).ceil
var total = 0
for (x in mins..maxs) {
var y = x * precision
var right = -1/0
var points = circles.where { |c| (y - c.y).abs < c.r }.map { |c| sect.call(c, y) }.toList
var cmp = Fn.new { |p1, p2| (p1.x - p2.x).sign }
Sort.insertion(points, cmp)
for (p in points) {
if (p.y > right) {
total = total + p.y - p.x.max(right)
right = p.y
}
}
}
return total * precision
}
var p = 1e-5
System.print("Approximate area = %(areaScan.call(p))")

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@ -0,0 +1,69 @@
real Circles, MinX, MaxX, MinY, MaxY, Temp, X, Y, DX, DY, Area;
int N, Cnt1, Cnt2;
def Del = 0.0005;
def Inf = float(-1>>1);
[\ X Y R
Circles:= [
1.6417233788, 1.6121789534, 0.0848270516,
-1.4944608174, 1.2077959613, 1.1039549836,
0.6110294452, -0.6907087527, 0.9089162485,
0.3844862411, 0.2923344616, 0.2375743054,
-0.2495892950, -0.3832854473, 1.0845181219,
1.7813504266, 1.6178237031, 0.8162655711,
-0.1985249206, -0.8343333301, 0.0538864941,
-1.7011985145, -0.1263820964, 0.4776976918,
-0.4319462812, 1.4104420482, 0.7886291537,
0.2178372997, -0.9499557344, 0.0357871187,
-0.6294854565, -1.3078893852, 0.7653357688,
1.7952608455, 0.6281269104, 0.2727652452,
1.4168575317, 1.0683357171, 1.1016025378,
1.4637371396, 0.9463877418, 1.1846214562,
-0.5263668798, 1.7315156631, 1.4428514068,
-1.2197352481, 0.9144146579, 1.0727263474,
-0.1389358881, 0.1092805780, 0.7350208828,
1.5293954595, 0.0030278255, 1.2472867347,
-0.5258728625, 1.3782633069, 1.3495508831,
-0.1403562064, 0.2437382535, 1.3804956588,
0.8055826339, -0.0482092025, 0.3327165165,
-0.6311979224, 0.7184578971, 0.2491045282,
1.4685857879, -0.8347049536, 1.3670667538,
-0.6855727502, 1.6465021616, 1.0593087096,
0.0152957411, 0.0638919221, 0.9771215985];
MinX:= +Inf; MaxX:= -Inf;
MinY:= +Inf; MaxY:= -Inf;
for N:= 0 to 25*3-1 do
[Temp:= Circles(N+0);
if Temp < 0.0 then Temp:= Temp - Circles(N+2)
else Temp:= Temp + Circles(N+2);
if Temp < MinX then MinX:= Temp;
if Temp > MaxX then MaxX:= Temp;
Temp:= Circles(N+1);
if Temp < 0.0 then Temp:= Temp - Circles(N+2)
else Temp:= Temp + Circles(N+2);
if Temp < MinY then MinY:= Temp;
if Temp > MaxY then MaxY:= Temp;
Circles(N+2):= sq(Circles(N+2)); \square for speed
N:= N+2;
];
Cnt1:= 0; Cnt2:= 0;
Y:= MinY;
repeat X:= MinX;
repeat
loop [for N:= 0 to 25*3-1 do
[DX:= X - Circles(N+0);
DY:= Y - Circles(N+1);
if DX*DX + DY*DY <= Circles(N+2) then
[Cnt1:= Cnt1+1; quit];
N:= N+2;
];
quit;
];
Cnt2:= Cnt2+1;
X:= X + Del;
until X >= MaxX;
Y:= Y + Del;
until Y >= MaxY;
Area:= (MaxX-MinX) * (MaxY-MinY); \of bounding box
Area:= float(Cnt1)/float(Cnt2) * Area; \of circles
RlOut(0, Area);
]

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@ -0,0 +1,26 @@
circles:=File("circles.txt").pump(List,'wrap(line){
line.split().apply("toFloat") // L(x,y,r)
});
# compute the bounding box of the circles
x_min:=(0.0).min(circles.apply(fcn([(x,y,r)]){ x - r })); // (0) not used, just the list of numbers
x_max:=(0.0).max(circles.apply(fcn([(x,y,r)]){ x + r }));
y_min:=(0.0).min(circles.apply(fcn([(x,y,r)]){ y - r }));
y_max:=(0.0).max(circles.apply(fcn([(x,y,r)]){ y + r }));
box_side:=500;
dx:=(x_max - x_min)/box_side;
dy:=(y_max - y_min)/box_side;
count:=0;
foreach r in (box_side){
y:=y_min + dy*r;
foreach c in (box_side){
x:=x_min + dx*c;
count+=circles.filter1('wrap([(cx,cy,cr)]){
x-=cx; y-=cy;
x*x + y*y <= cr*cr
}).toBool(); // -->False|L(x,y,z), L(x,y,r).toBool()-->True,
}
}
println("Approximated area: ", dx*dy*count);