#include <stdlib.h>
#include "pi.h"

static long count_in_circle(long N) /* count # of samples in circle        */
{
  long i, in;
  double x, y;
  
  for (i=in=0; i<N; i++)	/* find number of samples in circle        */
  {
    x = 2*drand48() - 1.0;	/* x coordinate                            */
    y = 2*drand48() - 1.0;	/* y coordinate                            */
    if (x*x + y*y < 1.0)	/* check if point (x,y) is in circle       */
      in++;
  }

  return in;
}



double EstimatePi(long N, int ProcessRank)
{
  int in;
  double pi;
  
  srand48(ProcessRank+1);

  in = count_in_circle(N);	/* count samples in circle                 */
  pi = (4.0*in)/(double) N;	/* estimate pi                             */

  return pi;
}

		   
#if 0
#include <stdio.h>

int main(int argc, char *argv[])
{
  long N;
  int ProcessRank;
  double pi;
  
  if(argc != 3)
  {
    fprintf(stderr,"USAGE: %s NumberOfSimulations ProcessRank\n", argv[0]);
    exit(-1);
  }
  
  N = atol(*++argv);
  ProcessRank = atoi(*++argv);
 
  pi = EstimatePi(N,ProcessRank);
  
  printf( "Pi is estimated as %f from %ld samples.\n", pi, N);

  return 0;
}

#endif