#include <stdio.h>
#include <sys/time.h>

long long num_steps = 1000000000;
double step;

int main(int argc, char* argv[])
{
    struct timeval TimeStampStart, TimeStampStop;
    double ExeTime;
    double x, pi, sum=0.0;
    int i;
    step = 1./(double)num_steps;
    
    gettimeofday(&TimeStampStart, NULL);
    
    for (i=0; i<num_steps; i++)
    {
        x = (i + .5)*step;
        sum = sum + 4.0/(1.+ x*x);
    }
    
    pi = sum*step;
    
    gettimeofday(&TimeStampStop, NULL);
    ExeTime = (double)(TimeStampStop.tv_sec - TimeStampStart.tv_sec) +
              (double)(TimeStampStop.tv_usec - TimeStampStart.tv_usec) * 1e-6;
    
    printf("The value of PI is %15.12f\n",pi);
    printf("The time to calculate PI was %f seconds\n", (ExeTime));
    
    return 0;
}