C example: PI

#include "mpi.h" 
#include <math.h> 
 
int main(argc,argv) 
int argc; 
char *argv[]; 
{ 
  int done = 0, n, myid, numprocs, i, rc; 
  double PI25DT = 3.141592653589793238462643; 
  double mypi, pi, h, sum, x, a; 
 
MPI_Init(&argc,&argv); 
  MPI_Comm_size(MPI_COMM_WORLD,&numprocs); 
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);