Data commit

Task/Minkowski-question-mark-function/FreeBASIC/minkowski-question-mark-function.basic

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+#define MAXITER 151
+
+function minkowski( x as double ) as double
+    if x>1 or x<0 then return int(x)+minkowski(x-int(x))
+    dim as ulongint p = int(x)
+    dim as ulongint q = 1, r = p + 1, s = 1, m, n
+    dim as double d = 1, y = p
+    while true
+        d = d / 2.0
+        if y + d = y then exit while
+        m = p + r
+        if m < 0 or p < 0 then exit while
+        n = q + s
+        if n < 0 then exit while
+        if x < cast(double,m) / n then
+            r = m
+            s = n
+        else
+            y = y + d
+            p = m
+            q = n
+        end if
+    wend
+    return y + d
+end function
+
+function minkowski_inv( byval x as double ) as double
+    if x>1 or x<0 then return int(x)+minkowski_inv(x-int(x))
+    if x=1 or x=0 then return x
+    redim as uinteger contfrac(0 to 0)
+    dim as uinteger curr=0, count=1, i = 0
+    do
+        x *= 2
+        if curr = 0 then
+            if x<1 then
+                count += 1
+            else
+                i += 1
+                redim preserve contfrac(0 to i)
+                contfrac(i-1)=count
+                count = 1
+                curr = 1
+                x=x-1
+            endif
+        else
+            if x>1 then
+                count += 1
+                x=x-1
+            else
+                i += 1
+                redim preserve contfrac(0 to i)
+                contfrac(i-1)=count
+                count = 1
+                curr = 0
+            endif
+        end if
+        if x = int(x) then
+            contfrac(i)=count
+            exit do
+        end if
+    loop until i = MAXITER
+    dim as double ret = 1.0/contfrac(i)
+    for j as integer = i-1 to 0 step -1
+        ret = contfrac(j) + 1.0/ret
+    next j
+    return 1./ret
+end function
+
+print minkowski( 0.5*(1+sqr(5)) ), 5./3
+print minkowski_inv( -5./9 ), (sqr(13)-7)/6
+print minkowski(minkowski_inv(0.718281828)), minkowski_inv(minkowski(0.1213141516171819))