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

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;Task:
Calculate the Feigenbaum constant.
;See:
:*   Details in the Wikipedia article:   [https://en.wikipedia.org/wiki/Feigenbaum_constants Feigenbaum constant].
<br><br>

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V max_it = 13
V max_it_j = 10
V a1 = 1.0
V a2 = 0.0
V d1 = 3.2
V a = 0.0
print( i d)
L(i) 2..max_it
a = a1 + (a1 - a2) / d1
L(j) 1..max_it_j
V x = 0.0
V y = 0.0
L(k) 1..(1 << i)
y = 1.0 - 2.0 * y * x
x = a - x * x
a = a - x / y
V d = (a1 - a2) / (a - a1)
print(#2 #.8.format(i, d))
d1 = d
a2 = a1
a1 = a

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# Calculate the Feigenbaum constant #
print( ( "Feigenbaum constant calculation:", newline ) );
INT max it = 13;
INT max it j = 10;
REAL a1 := 1.0;
REAL a2 := 0.0;
REAL d1 := 3.2;
print( ( "i ", "d", newline ) );
FOR i FROM 2 TO max it DO
REAL a := a1 + (a1 - a2) / d1;
FOR j TO max it j DO
REAL x := 0;
REAL y := 0;
FOR k TO 2 ^ i DO
y := 1 - 2 * y * x;
x := a - x * x
OD;
a := a - x / y
OD;
REAL d = (a1 - a2) / (a - a1);
IF i < 10 THEN
print( ( whole( i, 0 ), " ", fixed( d, -10, 8 ), newline ) )
ELSE
print( ( whole( i, 0 ), " ", fixed( d, -10, 8 ), newline ) )
FI;
d1 := d;
a2 := a1;
a1 := a
OD

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# syntax: GAWK -f FEIGENBAUM_CONSTANT_CALCULATION.AWK
BEGIN {
a1 = 1
a2 = 0
d1 = 3.2
max_i = 13
max_j = 10
print(" i d")
for (i=2; i<=max_i; i++) {
a = a1 + (a1 - a2) / d1
for (j=1; j<=max_j; j++) {
x = y = 0
for (k=1; k<=2^i; k++) {
y = 1 - 2 * y * x
x = a - x * x
}
a -= x / y
}
d = (a1 - a2) / (a - a1)
printf("%2d %.8f\n",i,d)
d1 = d
a2 = a1
a1 = a
}
exit(0)
}

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with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Main is
procedure feigenbaum is
subtype i_range is Integer range 2 .. 13;
subtype j_range is Integer range 1 .. 10;
-- the number of digits in type Real is reduced to 15 to produce the
-- results reported by C, C++, C# and Ring. Increasing the number of
-- digits in type Real produces the results reported by D.
type Real is digits 15;
package Real_Io is new Float_IO (Real);
use Real_Io;
a, x, y, d : Real;
a1 : Real := 1.0;
a2 : Real := 0.0;
d1 : Real := 3.2;
begin
Put_Line (" i d");
for i in i_range loop
a := a1 + (a1 - a2) / d1;
for j in j_range loop
x := 0.0;
y := 0.0;
for k in 1 .. 2**i loop
y := 1.0 - 2.0 * x * y;
x := a - x * x;
end loop;
a := a - x / y;
end loop;
d := (a1 - a2) / (a - a1);
Put (Item => i, Width => 2);
Put (Item => d, Fore => 5, Aft => 8, Exp => 0);
New_Line;
d1 := d;
a2 := a1;
a1 := a;
end loop;
end feigenbaum;
begin
feigenbaum;
end Main;

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maxIt = 13 : maxItj = 13
a1 = 1.0 : a2 = 0.0 : d = 0.0 : d1 = 3.2
print "Feigenbaum constant calculation:"
print
print " i d"
print "======================"
for i = 2 to maxIt
a = a1 + (a1 - a2) / d1
for j = 1 to maxItj
x = 0.0 : y = 0.0
for k = 1 to 2 ^ i
y = 1 - 2 * y * x
x = a - x * x
next k
a -= x / y
next j
d = (a1 - a2) / (a - a1)
print rjust(i,3); chr(9); ljust(d,13,"0")
d1 = d
a2 = a1
a1 = a
next i

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#include <iostream>
int main() {
const int max_it = 13;
const int max_it_j = 10;
double a1 = 1.0, a2 = 0.0, d1 = 3.2;
std::cout << " i d\n";
for (int i = 2; i <= max_it; ++i) {
double a = a1 + (a1 - a2) / d1;
for (int j = 1; j <= max_it_j; ++j) {
double x = 0.0;
double y = 0.0;
for (int k = 1; k <= 1 << i; ++k) {
y = 1.0 - 2.0*y*x;
x = a - x * x;
}
a -= x / y;
}
double d = (a1 - a2) / (a - a1);
printf("%2d %.8f\n", i, d);
d1 = d;
a2 = a1;
a1 = a;
}
return 0;
}

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using System;
namespace FeigenbaumConstant {
class Program {
static void Main(string[] args) {
var maxIt = 13;
var maxItJ = 10;
var a1 = 1.0;
var a2 = 0.0;
var d1 = 3.2;
Console.WriteLine(" i d");
for (int i = 2; i <= maxIt; i++) {
var a = a1 + (a1 - a2) / d1;
for (int j = 1; j <= maxItJ; j++) {
var x = 0.0;
var y = 0.0;
for (int k = 1; k <= 1<<i; k++) {
y = 1.0 - 2.0 * y * x;
x = a - x * x;
}
a -= x / y;
}
var d = (a1 - a2) / (a - a1);
Console.WriteLine("{0,2:d} {1:f8}", i, d);
d1 = d;
a2 = a1;
a1 = a;
}
}
}
}

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#include <stdio.h>
void feigenbaum() {
int i, j, k, max_it = 13, max_it_j = 10;
double a, x, y, d, a1 = 1.0, a2 = 0.0, d1 = 3.2;
printf(" i d\n");
for (i = 2; i <= max_it; ++i) {
a = a1 + (a1 - a2) / d1;
for (j = 1; j <= max_it_j; ++j) {
x = 0.0;
y = 0.0;
for (k = 1; k <= 1 << i; ++k) {
y = 1.0 - 2.0 * y * x;
x = a - x * x;
}
a -= x / y;
}
d = (a1 - a2) / (a - a1);
printf("%2d %.8f\n", i, d);
d1 = d;
a2 = a1;
a1 = a;
}
}
int main() {
feigenbaum();
return 0;
}

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import std.stdio;
void main() {
int max_it = 13;
int max_it_j = 10;
double a1 = 1.0;
double a2 = 0.0;
double d1 = 3.2;
double a;
writeln(" i d");
for (int i=2; i<=max_it; i++) {
a = a1 + (a1 - a2) / d1;
for (int j=1; j<=max_it_j; j++) {
double x = 0.0;
double y = 0.0;
for (int k=1; k <= 1<<i; k++) {
y = 1.0 - 2.0 * y * x;
x = a - x * x;
}
a -= x / y;
}
double d = (a1 - a2) / (a - a1);
writefln("%2d %.8f", i, d);
d1 = d;
a2 = a1;
a1 = a;
}
}

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procedure FeigenbaumConstant(Memo: TMemo);
{ Calculate the Feigenbaum constant }
const IMax = 13;
const JMax = 10;
var I,J,K: integer;
var A1,A2,D1,X,Y: double;
var A,D: double;
begin
Memo.Lines.Add('Feigenbaum constant calculation:');
{Set initial starting values for iterations}
A1:=1.0; A2:=0.0; D1:=3.2;
Memo.Lines.Add(' I A D');
for I:=2 to IMax do
begin
{Find next Bifurcation parameter, A}
A:=A1 + (A1 - A2) / D1;
for J:=1 to JMax do
begin
X:=0; Y:=0;
for K:=1 to 1 shl i do
begin
Y:=1 - 2 * y * x;
X:=A - X * X
end;
A:=A - X / Y
end;
{Use current and previous values of A}
{to calculate the Feigenbaum constant D }
D:= (A1 - A2) / (A - A1);
Memo.Lines.Add(Format('%2d %2.8f %2.8f',[I,A,D]));
D1:=D; A2:=A1; A1:=A;
end;
end;

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open System
[<EntryPoint>]
let main _ =
let maxIt = 13
let maxItJ = 10
let mutable a1 = 1.0
let mutable a2 = 0.0
let mutable d1 = 3.2
Console.WriteLine(" i d")
for i in 2 .. maxIt do
let mutable a = a1 + (a1 - a2) / d1
for j in 1 .. maxItJ do
let mutable x = 0.0
let mutable y = 0.0
for _ in 1 .. (1 <<< i) do
y <- 1.0 - 2.0 * y * x
x <- a - x * x
a <- a - x / y
let d = (a1 - a2) / (a - a1)
Console.WriteLine("{0,2:d} {1:f8}", i, d)
d1 <- d
a2 <- a1
a1 <- a
0 // return an integer exit code

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USING: formatting io locals math math.ranges sequences ;
[let
1 :> a1!
0 :> a2!
3.2 :> d!
" i d" print
2 13 [a,b] [| exp |
a1 a2 - d /f a1 + :> a!
10 [
0 :> x!
0 :> y!
exp 2^ [
1 2 x y * * - y!
a x sq - x!
] times
a x y /f - a!
] times
a1 a2 - a a1 - /f d!
a1 a2! a a1!
exp d "%2d %.8f\n" printf
] each
]

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program feigenbaum
implicit none
integer i, j, k
real ( KIND = 16 ) x, y, a, b, a1, a2, d1
print '(a4,a13)', 'i', 'd'
a1 = 1.0;
a2 = 0.0;
d1 = 3.2;
do i=2,20
a = a1 + (a1 - a2) / d1;
do j=1,10
x = 0
y = 0
do k=1,2**i
y = 1 - 2 * y * x;
x = a - x**2;
end do
a = a - x / y;
end do
d1 = (a1 - a2) / (a - a1);
a2 = a1;
a1 = a;
print '(i4,f13.10)', i, d1
end do
end

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' version 25-0-2019
' compile with: fbc -s console
Dim As UInteger i, j, k, maxit = 13, maxitj = 13
Dim As Double x, y, a, a1 = 1, a2, d, d1 = 3.2
Print "Feigenbaum constant calculation:"
Print
Print " i d"
Print "==================="
For i = 2 To maxIt
a = a1 + (a1 - a2) / d1
For j = 1 To maxItJ
x = 0 : y = 0
For k = 1 To 2 ^ i
y = 1 - 2 * y * x
x = a - x * x
Next
a = a - x / y
Next
d = (a1 - a2) / (a - a1)
Print Using "### ##.#########"; i; d
d1 = d
a2 = a1
a1 = a
Next
' empty keyboard buffer
While Inkey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End

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window 1, @"Feignenbaum Constant", ( 0, 0, 200, 300 )
_maxIt = 13
_maxItJ = 10
void local fn Feignenbaum
NSUInteger i, j, k
double a1 = 1.0, a2 = 0.0, d1 = 3.2
print "Feignenbaum Constant"
print " i d"
for i = 2 to _maxIt
double a = a1 + ( a1 - a2 ) / d1
for j = 1 to _maxItJ
double x = 0, y = 0
for k = 1 to fn pow( 2, i )
y = 1 - 2 * y * x
x = a - x * x
next
a = a - x / y
next
double d = ( a1 - a2 ) / ( a - a1 )
printf @"%2d. %.8f", i, d
d1 = d
a2 = a1
a1 = a
next
end fn
fn Feignenbaum
HandleEvents

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package main
import "fmt"
func feigenbaum() {
maxIt, maxItJ := 13, 10
a1, a2, d1 := 1.0, 0.0, 3.2
fmt.Println(" i d")
for i := 2; i <= maxIt; i++ {
a := a1 + (a1-a2)/d1
for j := 1; j <= maxItJ; j++ {
x, y := 0.0, 0.0
for k := 1; k <= 1<<uint(i); k++ {
y = 1.0 - 2.0*y*x
x = a - x*x
}
a -= x / y
}
d := (a1 - a2) / (a - a1)
fmt.Printf("%2d %.8f\n", i, d)
d1, a2, a1 = d, a1, a
}
}
func main() {
feigenbaum()
}

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class Feigenbaum {
static void main(String[] args) {
int max_it = 13
int max_it_j = 10
double a1 = 1.0
double a2 = 0.0
double d1 = 3.2
double a
println(" i d")
for (int i = 2; i <= max_it; i++) {
a = a1 + (a1 - a2) / d1
for (int j = 0; j < max_it_j; j++) {
double x = 0.0
double y = 0.0
for (int k = 0; k < 1 << i; k++) {
y = 1.0 - 2.0 * y * x
x = a - x * x
}
a -= x / y
}
double d = (a1 - a2) / (a - a1)
printf("%2d %.8f\n", i, d)
d1 = d
a2 = a1
a1 = a
}
}
}

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import Data.List (mapAccumL)
feigenbaumApprox :: Int -> [Double]
feigenbaumApprox mx = snd $ mitch mx 10
where
mitch :: Int -> Int -> ((Double, Double, Double), [Double])
mitch mx mxj =
mapAccumL
(\(a1, a2, d1) i ->
let a =
iterate
(\a ->
let (x, y) =
iterate
(\(x, y) -> (a - (x * x), 1.0 - ((2.0 * x) * y)))
(0.0, 0.0) !!
(2 ^ i)
in a - (x / y))
(a1 + (a1 - a2) / d1) !!
mxj
d = (a1 - a2) / (a - a1)
in ((a, a1, d), d))
(1.0, 0.0, 3.2)
[2 .. (1 + mx)]
-- TEST ------------------------------------------------------------------
main :: IO ()
main =
(putStrLn . unlines) $
zipWith
(\i s -> justifyRight 2 ' ' (show i) ++ '\t' : s)
[1 ..]
(show <$> feigenbaumApprox 13)
where
justifyRight n c s = drop (length s) (replicate n c ++ s)

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public class Feigenbaum {
public static void main(String[] args) {
int max_it = 13;
int max_it_j = 10;
double a1 = 1.0;
double a2 = 0.0;
double d1 = 3.2;
double a;
System.out.println(" i d");
for (int i = 2; i <= max_it; i++) {
a = a1 + (a1 - a2) / d1;
for (int j = 0; j < max_it_j; j++) {
double x = 0.0;
double y = 0.0;
for (int k = 0; k < 1 << i; k++) {
y = 1.0 - 2.0 * y * x;
x = a - x * x;
}
a -= x / y;
}
double d = (a1 - a2) / (a - a1);
System.out.printf("%2d %.8f\n", i, d);
d1 = d;
a2 = a1;
a1 = a;
}
}
}

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def feigenbaum_delta(imax; jmax):
def lpad: tostring | (" " * (4 - length)) + .;
def pp(i;x): "\(i|lpad) \(x)";
"Feigenbaum's delta constant incremental calculation:",
pp("i"; "δ"),
pp(1; "3.20"),
( foreach range(2; 1+imax) as $i (
{a1: 1.0, a2: 0.0, d1: 3.2};
.a = .a1 + (.a1 - .a2) / .d1
| reduce range(1; 1+jmax) as $j (.;
.x = 0 | .y = 0
| reduce range(1; 1+pow(2;$i)) as $k (.;
.y = (1 - 2 * .x * .y)
| .x = .a - (.x * .x) )
| .a -= (.x / .y) )
| .d = (.a1 - .a2) / (.a - .a1)
| .d1 = .d | .a2 = .a1 | .a1 = .a;
pp($i; .d) ) ) ;
Feigenbaum_delta(13; 10)

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Feigenbaum's delta constant incremental calculation:
i δ
1 3.20
2 3.2185114220380866
3 4.3856775985683365
4 4.600949276538056
5 4.6551304953919646
6 4.666111947822846
7 4.668548581451485
8 4.66906066077106
9 4.669171554514976
10 4.669195154039278
11 4.669200256503637
12 4.669200975097843
13 4.669205372040318

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# http://en.wikipedia.org/wiki/Feigenbaum_constant
function feigenbaum_delta(imax=23, jmax=20)
a1, a2, d1 = BigFloat(1.0), BigFloat(0.0), BigFloat(3.2)
println("Feigenbaum's delta constant incremental calculation:\ni δ\n1 3.20")
for i in 2:imax
a = a1 + (a1 - a2) / d1
for j in 1:jmax
x, y = 0, 0
for k in 1:2^i
y = 1 - 2 * x * y
x = a - x * x
end
a -= x / y
end
d = (a1 - a2) / (a - a1)
println(rpad(i, 4), lpad(d, 4))
d1, a2 = d, a1
a1 = a
end
end
feigenbaum_delta()

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// Version 1.2.40
fun feigenbaum() {
val maxIt = 13
val maxItJ = 10
var a1 = 1.0
var a2 = 0.0
var d1 = 3.2
println(" i d")
for (i in 2..maxIt) {
var a = a1 + (a1 - a2) / d1
for (j in 1..maxItJ) {
var x = 0.0
var y = 0.0
for (k in 1..(1 shl i)) {
y = 1.0 - 2.0 * y * x
x = a - x * x
}
a -= x / y
}
val d = (a1 - a2) / (a - a1)
println("%2d %.8f".format(i,d))
d1 = d
a2 = a1
a1 = a
}
}
fun main(args: Array<String>) {
feigenbaum()
}

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{feigenbaum 11} // on my computer stackoverflow for values greater than 11
-> [3.2185114220380866,4.3856775985683365,4.600949276538056,4.6551304953919646,4.666111947822846,
4.668548581451485,4.66906066077106,4.669171554514976,4.669195154039278,4.669200256503637]
with:
{def feigenbaum
{lambda {:maxi}
{f3 :maxi 10 1 0 3.2 0 {A.new} 2}}}
{def f3
{lambda {:maxi :maxj :a1 :a2 :d1 :a3 :s :i}
{if {< :i {+ :maxi 1}}
then {let { {:maxi :maxi} {:maxj :maxj} {:a1 :a1} {:a2 :a2}
{:a3 {f2 {+ :a1 {/ {- :a1 :a2} :d1}} :i :maxj 1} }
{:s :s} {:i :i}
} {f3 :maxi :maxj :a3 :a1 {/ {- :a1 :a2} {- :a3 :a1}} :a3
{A.addlast! {/ {- :a1 :a2} {- :a3 :a1}} :s} {+ :i 1}} }
else :s}}}
{def f2
{lambda {:a :i :maxj :j}
{if {< :j {+ :maxj 1}}
then {f2 {f1 :a :i 0 0 1} :i :maxj {+ :j 1}}
else :a}}}
{def f1
{lambda {:a :i :y :x :k}
{if {< :k {+ {pow 2 :i} 1}}
then {f1 :a :i {- 1 {* 2 :y :x}} {- :a {* :x :x}} {+ :k 1}}
else {- :a {/ :x :y}} }}}

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function leftShift(n,p)
local r = n
while p>0 do
r = r * 2
p = p - 1
end
return r
end
-- main
local MAX_IT = 13
local MAX_IT_J = 10
local a1 = 1.0
local a2 = 0.0
local d1 = 3.2
print(" i d")
for i=2,MAX_IT do
local a = a1 + (a1 - a2) / d1
for j=1,MAX_IT_J do
local x = 0.0
local y = 0.0
for k=1,leftShift(1,i) do
y = 1.0 - 2.0 * y * x
x = a - x * x
end
a = a - x / y
end
d = (a1 - a2) / (a - a1)
print(string.format("%2d %.8f", i, d))
d1 = d
a2 = a1
a1 = a
end

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module Feigenbaum_constant_calculation (maxit as integer, c as single){
locale 1033 // show dot for decimal separator symbol
single maxitj=13
integer i, j
long k
decimal a1=1, a2, d , d1=3.2, y, x, a
print "Feigenbaum constant calculation:"
print
print format$("{0:-7} {1:-12} {2}","i", "δ","max j")
for i = 2 to maxit
a=a1+(a1-a2)/d1
for j = 1 to maxitj {x=0:y=0:for k=1 to 2&^i {y=1@-2@*y*x:x=a-x*x}:a-=x/y}
d=(a1-a2)/(a-a1)
print format$("{0::-7} {1:10:-12} {2::-5}",i, d, j-1)
maxitj-=c
d1=d:a2=a1:a1= a
next
}
profiler
Feigenbaum_constant_calculation 18, .7
print timecount

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maxit = 13;
maxitj = 10;
a1 = 1.0;
a2 = 0.0;
d1 = 3.2;
a = 0.0;
Table[
a = a1 + (a1 - a2)/d1;
Do[
x = 0.0;
y = 0.0;
Do[
y = 1.0 - 2.0 y x;
x = a - x x;
,
{k, 1, 2^i}
];
a = a - x/y
,
{j, maxitj}
];
d = (a1 - a2)/(a - a1);
d1 = d;
a2 = a1;
a1 = a;
{i, d}
,
{i, 2, maxit}
] // Grid

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MODULE Feigenbaum;
FROM FormatString IMPORT FormatString;
FROM LongStr IMPORT RealToStr;
FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
VAR
buf : ARRAY[0..63] OF CHAR;
i,j,k,max_it,max_it_j : INTEGER;
a,x,y,d,a1,a2,d1 : LONGREAL;
BEGIN
max_it := 13;
max_it_j := 10;
a1 := 1.0;
a2 := 0.0;
d1 := 3.2;
WriteString(" i d");
WriteLn;
FOR i:=2 TO max_it DO
a := a1 + (a1 - a2) / d1;
FOR j:=1 TO max_it_j DO
x := 0.0;
y := 0.0;
FOR k:=1 TO INT(1 SHL i) DO
y := 1.0 - 2.0 * y * x;
x := a - x * x
END;
a := a - x / y
END;
d := (a1 - a2) / (a - a1);
FormatString("%2i ", buf, i);
WriteString(buf);
RealToStr(d, buf);
WriteString(buf);
WriteLn;
d1 := d;
a2 := a1;
a1 := a
END;
ReadChar
END Feigenbaum.

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import strformat
iterator feigenbaum(): tuple[n: int; δ: float] =
## Yield successive approximations of Feigenbaum constant.
const
MaxI = 13
MaxJ = 10
var
a1 = 1.0
a2 = 0.0
δ = 3.2
for i in 2..MaxI:
var a = a1 + (a1 - a2) / δ
for j in 1..MaxJ:
var x, y = 0.0
for _ in 1..(1 shl i):
y = 1 - 2 * y * x
x = a - x * x
a -= x / y
δ = (a1 - a2) / (a - a1)
a2 = a1
a1 = a
yield (i, δ)
echo " i δ"
for n, δ in feigenbaum():
echo fmt"{n:2d} {δ:.8f}"

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use strict;
use warnings;
use Math::AnyNum 'sqr';
my $a1 = 1.0;
my $a2 = 0.0;
my $d1 = 3.2;
print " i δ\n";
for my $i (2..13) {
my $a = $a1 + ($a1 - $a2)/$d1;
for (1..10) {
my $x = 0;
my $y = 0;
for (1 .. 2**$i) {
$y = 1 - 2 * $y * $x;
$x = $a - sqr($x);
}
$a -= $x/$y;
}
$d1 = ($a1 - $a2) / ($a - $a1);
($a2, $a1) = ($a1, $a);
printf "%2d %17.14f\n", $i, $d1;
}

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(phixonline)-->
<span style="color: #008080;">constant</span> <span style="color: #000000;">maxIt</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">13</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">maxItJ</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">10</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">a1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1.0</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">a2</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0.0</span><span style="color: #0000FF;">,</span>
<span style="color: #000000;">d1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">3.2</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" i d\n"</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;">2</span> <span style="color: #008080;">to</span> <span style="color: #000000;">maxIt</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a1</span> <span style="color: #0000FF;">+</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">a1</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">a2</span><span style="color: #0000FF;">)</span> <span style="color: #0000FF;">/</span> <span style="color: #000000;">d1</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">j</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #000000;">maxItJ</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">x</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">y</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">k</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">power</span><span style="color: #0000FF;">(</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">y</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">2</span><span style="color: #0000FF;">*</span><span style="color: #000000;">y</span><span style="color: #0000FF;">*</span><span style="color: #000000;">x</span>
<span style="color: #000000;">x</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a</span> <span style="color: #0000FF;">-</span> <span style="color: #000000;">x</span><span style="color: #0000FF;">*</span><span style="color: #000000;">x</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #000000;">a</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a</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: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #004080;">atom</span> <span style="color: #000000;">d</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">(</span><span style="color: #000000;">a1</span><span style="color: #0000FF;">-</span><span style="color: #000000;">a2</span><span style="color: #0000FF;">)/(</span><span style="color: #000000;">a</span><span style="color: #0000FF;">-</span><span style="color: #000000;">a1</span><span style="color: #0000FF;">)</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;">"%2d %.8f\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">i</span><span style="color: #0000FF;">,</span><span style="color: #000000;">d</span><span style="color: #0000FF;">})</span>
<span style="color: #000000;">d1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">d</span>
<span style="color: #000000;">a2</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a1</span>
<span style="color: #000000;">a1</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">a</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--

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max_it = 13
max_it_j = 10
a1 = 1.0
a2 = 0.0
d1 = 3.2
a = 0.0
print " i d"
for i in range(2, max_it + 1):
a = a1 + (a1 - a2) / d1
for j in range(1, max_it_j + 1):
x = 0.0
y = 0.0
for k in range(1, (1 << i) + 1):
y = 1.0 - 2.0 * y * x
x = a - x * x
a = a - x / y
d = (a1 - a2) / (a - a1)
print("{0:2d} {1:.8f}".format(i, d))
d1 = d
a2 = a1
a1 = a

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/*REXX pgm calculates the (Mitchell) Feigenbaum bifurcation velocity, #digs can be given*/
parse arg digs maxi maxj . /*obtain optional argument from the CL.*/
if digs=='' | digs=="," then digs= 30 /*Not specified? Then use the default.*/
if maxi=='' | maxi=="," then maxi= 20 /* " " " " " " */
if maxJ=='' | maxJ=="," then maxJ= 10 /* " " " " " " */
#= 4.669201609102990671853203820466201617258185577475768632745651343004134330211314737138,
|| 68974402394801381716 /*◄──Feigenbaum's constant, true value.*/
numeric digits digs /*use the specified # of decimal digits*/
a1= 1
a2= 0
d1= 3.2
say 'Using ' maxJ " iterations for maxJ, with " digs ' decimal digits:'
say
say copies(' ', 9) center("correct", 11) copies(' ', digs+1)
say center('i', 9, "") center('digits' , 11, "") center('d', digs+1, "")
do i=2 for maxi-1
a= a1 + (a1 - a2) / d1
do maxJ
x= 0; y= 0
do 2**i; y= 1 - 2 * x * y
x= a - x*x
end /*2**i*/
a= a - x / y
end /*maxj*/
d= (a1 - a2) / (a - a1) /*compute the delta (D) of the function*/
t= max(0, compare(d, #) - 2) /*# true digs so far, ignore dec. point*/
say center(i, 9) center(t, 11) d /*display values for I & D ──►terminal*/
parse value d a1 a with d1 a2 a1 /*assign 3 variables with 3 new values.*/
end /*i*/
/*stick a fork in it, we're all done. */
say left('', 9 + 1 + 11 + 1 + t )"" /*show position of greatest accuracy. */
say ' true value= ' # / 1 /*true value of Feigenbaum's constant. */

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#lang racket
(define (feigenbaum #:max-it (max-it 13) #:max-it-j (max-it-j 10))
(displayln " i d" (current-error-port))
(define-values (_a _a1 d)
(for/fold ((a 1) (a1 0) (d 3.2))
((i (in-range 2 (add1 max-it))))
(let* ((a (for/fold ((a (+ a (/ (- a a1) d))))
((j (in-range max-it-j)))
(let-values (([x y] (for/fold ((x 0) (y 0))
((k (expt 2 i)))
(values (- a (* x x))
(- 1 (* 2 y x))))))
(- a (/ x y)))))
(d (/ (- a a1) (- a a))))
(eprintf "~a ~a\n" (~a i #:width 2) (real->decimal-string d 8))
(values a a d))))
d)
(module+ main
(feigenbaum))

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my $a1 = 1;
my $a2 = 0;
my $d = 3.2;
say ' i d';
for 2 .. 13 -> $exp {
my $a = $a1 + ($a1 - $a2) / $d;
do {
my $x = 0;
my $y = 0;
for ^2 ** $exp {
$y = 1 - 2 * $y * $x;
$x = $a - $x²;
}
$a -= $x / $y;
} xx 10;
$d = ($a1 - $a2) / ($a - $a1);
($a2, $a1) = ($a1, $a);
printf "%2d %.8f\n", $exp, $d;
}

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# Project : Feigenbaum constant calculation
decimals(8)
see "Feigenbaum constant calculation:" + nl
maxIt = 13
maxItJ = 10
a1 = 1.0
a2 = 0.0
d1 = 3.2
see "i " + "d" + nl
for i = 2 to maxIt
a = a1 + (a1 - a2) / d1
for j = 1 to maxItJ
x = 0
y = 0
for k = 1 to pow(2,i)
y = 1 - 2 * y * x
x = a - x * x
next
a = a - x / y
next
d = (a1 - a2) / (a - a1)
if i < 10
see "" + i + " " + d + nl
else
see "" + i + " " + d + nl
ok
d1 = d
a2 = a1
a1 = a
next

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@ -0,0 +1,27 @@
def main
maxIt = 13
maxItJ = 10
a1 = 1.0
a2 = 0.0
d1 = 3.2
puts " i d"
for i in 2 .. maxIt
a = a1 + (a1 - a2) / d1
for j in 1 .. maxItJ
x = 0.0
y = 0.0
for k in 1 .. 1 << i
y = 1.0 - 2.0 * y * x
x = a - x * x
end
a = a - x / y
end
d = (a1 - a2) / (a - a1)
print "%2d %.8f\n" % [i, d]
d1 = d
a2 = a1
a1 = a
end
end
main()

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object Feigenbaum1 extends App {
val (max_it, max_it_j) = (13, 10)
var (a1, a2, d1, a) = (1.0, 0.0, 3.2, 0.0)
println(" i d")
var i: Int = 2
while (i <= max_it) {
a = a1 + (a1 - a2) / d1
for (_ <- 0 until max_it_j) {
var (x, y) = (0.0, 0.0)
for (_ <- 0 until 1 << i) {
y = 1.0 - 2.0 * y * x
x = a - x * x
}
a -= x / y
}
val d: Double = (a1 - a2) / (a - a1)
printf("%2d %.8f\n", i, d)
d1 = d
a2 = a1
a1 = a
i += 1
}
}

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object Feigenbaum2 extends App {
private val (max_it, max_it_j) = (13, 10)
private def result = {
@scala.annotation.tailrec
def outer(i: Int, d1: Double, a2: Double, a1: Double, acc: Seq[Double]): Seq[Double] = {
@scala.annotation.tailrec
def center(j: Int, a: Double): Double = {
@scala.annotation.tailrec
def inner(k: Int, end: Int, x: Double, y: Double): (Double, Double) =
if (k < end) inner(k + 1, end, a - x * x, 1.0 - 2.0 * y * x) else (x, y)
val (x, y) = inner(0, 1 << i, 0.0, 0.0)
if (j < max_it_j) {
center(j + 1, a - (x / y))
} else a
}
if (i <= max_it) {
val a = center(0, a1 + (a1 - a2) / d1)
val d: Double = (a1 - a2) / (a - a1)
outer(i + 1, d, a1, a, acc :+ d)
} else acc
}
outer(2, 3.2, 0, 1.0, Seq[Double]()).zipWithIndex
}
println(" i ≈ δ")
result.foreach { case (δ, i) => println(f"${i + 2}%2d %.8f") }
}

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var a1 = 1
var a2 = 0
var δ = 3.2.float
say " i\tδ"
for i in (2..15) {
var a0 = ((a1 - a2)/δ + a1)
10.times {
var (x, y) = (0, 0)
2**i -> times {
y = (1 - 2*x*y)
x = (a0 - x²)
}
a0 -= x/y
}
δ = ((a1 - a2) / (a0 - a1))
(a2, a1) = (a1, a0)
printf("%2d %.8f\n", i, δ)
}

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import Foundation
func feigenbaum(iterations: Int = 13) {
var a = 0.0
var a1 = 1.0
var a2 = 0.0
var d = 0.0
var d1 = 3.2
print(" i d")
for i in 2...iterations {
a = a1 + (a1 - a2) / d1
for _ in 1...10 {
var x = 0.0
var y = 0.0
for _ in 1...1<<i {
y = 1.0 - 2.0 * y * x
x = a - x * x
}
a -= x / y
}
d = (a1 - a2) / (a - a1)
d1 = d
(a1, a2) = (a, a1)
print(String(format: "%2d %.8f", i, d))
}
}
feigenbaum()

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LET maxit = 13
LET maxitj = 13
LET a1 = 1.0
LET d1 = 3.2
PRINT "Feigenbaum constant calculation:"
PRINT
PRINT " i d"
PRINT "==================="
FOR i = 2 to maxit
LET a = a1 + (a1 - a2) / d1
FOR j = 1 to maxitj
LET x = 0
LET y = 0
FOR k = 1 to 2 ^ i
LET y = 1 - 2 * y * x
LET x = a - x * x
NEXT k
LET a = a - (x / y)
NEXT j
LET d = (a1 - a2) / (a - a1)
PRINT using "### ##.#########": i, d
LET d1 = d
LET a2 = a1
LET a1= a
NEXT i
END

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@ -0,0 +1,23 @@
fn feigenbaum() {
max_it, max_itj := 13, 10
mut a1, mut a2, mut d1 := 1.0, 0.0, 3.2
println(" i d")
for i := 2; i <= max_it; i++ {
mut a := a1 + (a1-a2)/d1
for j := 1; j <= max_itj; j++ {
mut x, mut y := 0.0, 0.0
for k := 1; k <= 1<<u32(i); k++ {
y = 1.0 - 2.0*y*x
x = a - x*x
}
a -= x / y
}
d := (a1 - a2) / (a - a1)
println("${i:2} ${d:.8f}")
d1, a2, a1 = d, a1, a
}
}
fn main() {
feigenbaum()
}

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Module Module1
Sub Main()
Dim maxIt = 13
Dim maxItJ = 10
Dim a1 = 1.0
Dim a2 = 0.0
Dim d1 = 3.2
Console.WriteLine(" i d")
For i = 2 To maxIt
Dim a = a1 + (a1 - a2) / d1
For j = 1 To maxItJ
Dim x = 0.0
Dim y = 0.0
For k = 1 To 1 << i
y = 1.0 - 2.0 * y * x
x = a - x * x
Next
a -= x / y
Next
Dim d = (a1 - a2) / (a - a1)
Console.WriteLine("{0,2:d} {1:f8}", i, d)
d1 = d
a2 = a1
a1 = a
Next
End Sub
End Module

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import "/fmt" for Fmt
var feigenbaum = Fn.new {
var maxIt = 13
var maxItJ = 10
var a1 = 1
var a2 = 0
var d1 = 3.2
System.print(" i d")
for (i in 2..maxIt) {
var a = a1 + (a1 - a2)/d1
for (j in 1..maxItJ) {
var x = 0
var y = 0
for (k in 1..(1<<i)) {
y = 1 - 2*y*x
x = a - x*x
}
a = a - x/y
}
var d = (a1 - a2)/(a - a1)
System.print("%(Fmt.d(2, i)) %(Fmt.f(0, d, 8))")
d1 = d
a2 = a1
a1 = a
}
}
feigenbaum.call()

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def MaxIt = 13, MaxItJ = 10;
real A, A1, A2, D, D1, X, Y;
int I, J, K;
[A1:= 1.; A2:= 0.; D1:= 3.2;
Text(0, " i d^m^j");
for I:= 2 to MaxIt do
[A:= A1 + (A1-A2)/D1;
for J:= 1 to MaxItJ do
[X:= 0.; Y:= 0.;
for K:= 1 to 1<<I do
[Y:= 1. - 2.*Y*X;
X:= A - X*X;
];
A:= A - X/Y;
];
D:= (A1-A2) / (A-A1);
Format(2, 0); RlOut(0, float(I));
Format(5, 8); RlOut(0, D);
CrLf(0);
D1:= D;
A2:= A1;
A1:= A;
];
]

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maxIt = 13 : maxItj = 13
a1 = 1.0 : a2 = 0.0 : d = 0.0 : d1 = 3.2
print "Feigenbaum constant calculation:"
print "\n i d"
print "===================="
for i = 2 to maxIt
a = a1 + (a1 - a2) / d1
for j = 1 to maxItj
x = 0.0 : y = 0.0
for k = 1 to 2 ^ i
y = 1 - 2 * y * x
x = a - x * x
next k
a = a - x / y
next j
d = (a1 - a2) / (a - a1)
print i using("###"), chr$(9), d
d1 = d
a2 = a1
a1 = a
next i

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fcn feigenbaum{
maxIt,maxItJ,a1,a2,d1,a,d := 13, 10, 1.0, 0.0, 3.2, 0, 0;
println(" i d");
foreach i in ([2..maxIt]){
a=a1 + (a1 - a2)/d1;
foreach j in ([1..maxItJ]){
x,y := 0.0, 0.0;
foreach k in ([1..(1).shiftLeft(i)]){ y,x = 1.0 - 2.0*y*x, a - x*x; }
a-=x/y
}
d=(a1 - a2)/(a - a1);
println("%2d %.8f".fmt(i,d));
d1,a2,a1 = d,a1,a;
}
}();