Program to compute Pi using Monte Carlo methods

monte-carlo-pi-srand.c

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>

#define SEED 35791246

int main(int argc, char* argv) {
    int niter = 1UL << 20;
    double x, y;
 
    /* number of points in the 1st quadrant of unit circle */
    int count = 0; 
    double rsqure;
 
    printf("Enter the number of iterations used to estimate pi: %d", niter);
    // scanf("%d", &niter);
 
    /* initialize random numbers */
    srand(SEED);
 
    for (int i = 0; i < niter; i++) {
        x = (double) rand() / RAND_MAX;
        y = (double) rand() / RAND_MAX;
        rsqure = x * x + y * y;
 
        // deterministic algorithm, x^2 + y^2 <= 1
        if (rsqure <= 1)
            count++;
    }

    double pi = (double) count / niter * 4;
    printf("# of trials = %d , estimate of pi is %g \n", niter, pi);
}