#include <math.h>
#include <stdio.h>

int main(void)
{
   double   two_pi = 2.0 * M_PI;   /* in math.h */
   double   h      = 0.1;          /* step size */
   double   x;

   for (x = 0.0; x < two_pi; x += h)
      printf("%5.1f: %.15e\n",
         x, sin(x) * sin(x) + cos(x) * cos(x));
   return 0;
}