<pre name="code" class="cpp">#include<stdio.h>

#include<time.h>

#include<omp.h>

 

static long num_steps = 100000;

double step,pi;

void main()

{

    clock_t t1=clock();

    int i;

    double x,sum = 0.0;

    step = 1.0/(double)num_steps;

#pragma omp parallel for reduction(+:sum)

    for(i = 0;i<num_steps;i++)

    {

        x = (i+0.5)*step;

        sum = sum + 4.0/(1.0+x*x);

        printf("%d",omp_get_thread_num());

    }

    pi = step *sum;

    clock_t t2 =clock();

    printf("pi=%f,用时:%d\n",pi,t2-t1);

}

Open MP计算π的值