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/*
* Stolen from gnumeric
*
* Original code from Morten Welinder <terra@gnome.org>
*/
#include <stdio.h>
#include <limits.h>
#include "continued-fraction.h"
void continued_fraction(double val, int max_denom, int *res_num, int *res_denom) {
int n1, n2, d1, d2;
double x, y;
if (val < 0) {
continued_fraction (-val, max_denom, res_num, res_denom);
*res_num = -*res_num;
return;
}
n1 = 0; d1 = 1;
n2 = 1; d2 = 0;
x = val;
y = 1;
do {
int a = (int) (x / y);
double newy = x - a * y;
int n3, d3;
if ((n2 && a > (INT_MAX - n1) / n2) ||
(d2 && a > (INT_MAX - d1) / d2) ||
a * d2 + d1 > max_denom) {
*res_num = n2;
*res_denom = d2;
return;
}
n3 = a * n2 + n1;
d3 = a * d2 + d1;
x = y;
y = newy;
n1 = n2; n2 = n3;
d1 = d2; d2 = d3;
} while (y > 1e-10);
*res_num = n2;
*res_denom = d2;
}
#if 0
int main(int argc, char*argv[]) {
float value = 3.1417235;
int res_num, res_denom;
continued_fraction(value, 0xFFFF, &res_num, &res_denom);
printf("%g ~= %i/%i = %g\n", value, res_num, res_denom, (float) res_num / res_denom);
return 0;
}
#endif
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