// gcc aip.c test.c -Wmost -fnested-functions -O3
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
typedef float real; // could be double.
double max(double x, double y){return x<y?y:x;};
#define C const
double C pi = 3.1415926535897932;
typedef struct{real x; real y;} point;
real inter(int, point[], int, point[]);
int main(){point a[3], b[3]; double me=0;
  double C pio3 = pi/3., sr3o2 = sqrt(3)/2;
  {double th; for(th = 0; th < 3; th += 0.00001) {
     a[0] = (point){cos(th), sin(th)};
     b[0] = (point){cos(th+pio3), sin(th+pio3)};
     a[1] = (point){cos(th+2*pio3), sin(th+2*pio3)};
     b[1] = (point){cos(th+3*pio3), sin(th+3*pio3)};
     a[2] = (point){cos(th+4*pio3), sin(th+4*pio3)};
     b[2] = (point){cos(th+5*pio3), sin(th+5*pio3)};
     real A = inter(3, a, 3, b);
     me = max(me, fabs(A - sr3o2));}
     printf("Max error = %e\n", me);}
return 0;}