MPI Hello World - 1

Here is the Hello World Sample.

	#include <stdio.h>
	#include "mpi.h"
	int main (int argc, char *argv[])
	{
	int rank, nprocs;
	MPI_Init (&argc, &argv);
	/* creates MPI execution environment */
	MPI_Comm_rank (MPI_COMM_WORLD, &rank);
	/* get current process rank */
	MPI_Comm_size (MPI_COMM_WORLD, &nprocs);
	/* get number of processes */
	printf("Hello world from process %d of %d\n", rank, nprocs);
	MPI_Finalize();
	/* terminates the MPI execution environment */
	}

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Compile it using

mpicc helloworld.c

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Execute it using

mpirun -np 5 ./a.out

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Here is the Hello World Sample for Python. You cannot execute it in CC server but you can install the mpi4py module on your workstation

	#!/usr/bin/env python
	from mpi4py import MPI
	comm = MPI.COMM_WORLD
	print "Hello! I'm rank %d from %d running in total..." % (comm.rank, comm.size)
	comm.Barrier()
	#Waits for all process to synchronize _here_
	#It is optional as it just allows Hello World to be printed in order 0 ... n-1

view raw helloworld_with_barrier.py hosted with ❤ by GitHub

Execute it using

mpirun -np 4 helloworld_with_barrier.py

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Lecture
MPI Hello World - 2
MPI Pi Calculation