Question

monte carlo pi estimation using MPI in C

Answer 1

• Program

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#define SEED 35791246

main(int argc, char* argv)
{
int niter=0;
double x,y;
int i,count=0; /* # of points in the 1st quadrant of unit circle */
double z;
double pi;

printf("Enter the number of iterations used to estimate pi: ");
scanf("%d",&niter);

/* initialize random numbers */
srand(SEED);
count=0;
for ( i=0; i<niter; i++) {
x = (double)rand()/RAND_MAX;
y = (double)rand()/RAND_MAX;
z = x*x+y*y;
if (z<=1) count++;
}
pi=(double)count/niter*4;
printf("# of trials= %d , estimate of pi is %g \n",niter,pi);

return 0;
}

• Output

Enter the number of iterations used to estimate pi: 1000

# of trials= 1000 , estimate of pi is 3.172