pi_omp.c

#include <omp.h>
#include <stdio.h> 

main() {

 double pi = 0.0; 
 long i;
 int N = 100000 ; 
#pragma omp parallel for reduction(+:pi)
 for (i=0; i<N; i++) {
	 double t = (double)((i+0.05)/N);
	 pi += 4.0/(1.0+t*t);
 }
 printf("pi = %f with N %d \n", pi/N, N);
}