MPI-nparticles

[athenaabc]

The program that i wrote must calculate n changes of position on n particles, but the program doesn't work if number of position to calculate >1. Please tell me where i wrong

#include "stdafx.h"
#include <stdio.h>
#include "mpi.h"
#include <time.h>
#define part 3
#define poz 2

int main(int argc, char *argv[])
{
	int i, j, k, numprocs, myrank, id, f, n=0, t;
	float X[part], F[part],F1[part], F_all[part] , Fij=0.0;

	MPI_Status status;
	MPI_Init(&argc,&argv);
	MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
	MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
	
	if(myrank==0)
	{
		n=part;
		for(i=0;i<n;i++)
		{
		X[i]= i+1.0;
		}
		for(t=0;t<poz;t++)
		{
			for ( id = 1; id < numprocs; id++ ) 
			{
				MPI_Send( &n, 1, MPI_FLOAT, id, 123, MPI_COMM_WORLD );
				MPI_Send( &X, n, MPI_FLOAT, id, 123, MPI_COMM_WORLD );    	
			}
			for(k=0;k<n;k++)
			F[k]=0.0;
			for(i=0+myrank;i<n-1;i+=numprocs)
				for(j=i+1;j<n;j++)
				{
					Fij=1.0/(X[j]-X[i]);
					F[i]=F[i]+Fij;
					F[j]=F[j]-Fij;
				}
			for(i=0;i<n;i++)
			{
				F1[i]=0.0;
				F1[i]=F[i];
			}
			for(i=0;i<n;i++)
				F_all[i]=0.0;
			for ( id= 1; id< numprocs; id++ ) 
			{
				MPI_Recv ( &F, n, MPI_FLOAT, id, 123 , MPI_COMM_WORLD, &status );
				for(f=0;f<n;f++)	
					F_all[f] = F_all[f]+F[f];
			}
			for(i=0;i<n;i++)
			{
				F_all[i] = F_all[i]+F1[i];
				printf("F_all[%d]=%f\n",i ,  F_all[i]);	
			}	
			for(i=0;i<n;i++)
			{
				X[i]= X[i]+F_all[i];
				printf("X[%d]=%f\n",i, X[i]);
			}
		}	
}
	else
	{
		MPI_Recv( &n, 1, MPI_FLOAT, 0, 123, MPI_COMM_WORLD, &status);
		MPI_Recv( &X, n, MPI_FLOAT, 0, 123, MPI_COMM_WORLD, &status);
		for(k=0;k<n;k++)
			F[k]=0.0;
		for(i=0+myrank;i<n-1;i+=numprocs)
			for(j=i+1;j<n;j++)
			{
				Fij=1.0/(X[j]-X[i]);
				F[i]=F[i]+Fij;
				F[j]=F[j]-Fij;
			}
		
		MPI_Send ( &F, n, MPI_FLOAT, 0, 123, MPI_COMM_WORLD );
	 }
	MPI_Finalize();
	return 0;
}

[tabstop]

What "doesn't work" about it? Does it hold up picket signs? Does it crash? Does it give erroneous output? Does it just run forever? What?

[athenaabc]

Program return result only if must calculate only one change of position. If i use loop to calculate more then one changing program doesn't return result.

[tabstop]

This makes me nervous:

MPI_Recv( &n, 1, MPI_FLOAT, 0, 123, MPI_COMM_WORLD, &status);

n is not a float. True, you're sending it as a float, but that doesn't really help; and sizeof float doesn't have to equal sizeof int.