/*
  Calcul de pi 
  Author: O. Coulaud
  

 */
static long num_steps = 10000;
double step;
int main ()
{	 
  int i; 
  double x, pi, sum = 0.0;
  double PI25DT = 3.141592653589793238462643;

  step = 1.0/(double) num_steps;
  
  for (i=1;i<= num_steps; i++){
    x = (i-0.5)*step;
    sum = sum + 4.0/(1.0+x*x);
  }
  pi = step * sum;
  printf("pi := %.16e  %.e\n", pi, fabs(pi - PI25DT));
  return 0 ;
}