#include <omp.h>
static long num_steps = 100000;	double step;
#define NUM_THREADS 2
void main ()
{
	int i, nthreads;	
	double pi, sum[NUM_THREADS];
	step = 1.0/(double) num_steps;
	omp_set_num_threads(NUM_THREADS);
	#pragma omp parallel
	{
		int i, id,nthrds;
		double x;
		id = omp_get_thread_num();  
		nthrds = omp_get_num_threads();
		if (id == 0)	nthreads = nthrds;
		for (i=id, sum[id]=0.0;i< num_steps; i=i+nthrds) {  
			x = (i+0.5)*step;
			sum[id] += 4.0/(1.0+x*x);
		}
	}
	for(i=0, pi=0.0;i<nthreads;i++) pi += sum[i] * step
}