send the third column of a matrix from process 0 to * process 1

/* send_col.c -- send the third column of a matrix from process 0 to
* process 1
*
* Input: None
* Output: The column received by process 1
*
* Note: This program should only be run with 2 processes
*
* See Chap 6., pp. 96 & ff in PPMPI
*/
#include
#include "mpi.h"

main(int argc, char* argv[]) {
int p;
int my_rank;
float A[10][10];
MPI_Status status;
MPI_Datatype column_mpi_t;
int i, j;

MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);

MPI_Type_vector(10, 1, 10, MPI_FLOAT, &column_mpi_t);
MPI_Type_commit(&column_mpi_t);

if (my_rank == 0) {
for (i = 0; i < 10; i++)
for (j = 0; j < 10; j++)
A[i][j] = (float) j;
MPI_Send(&(A[0][2]), 1, column_mpi_t, 1, 0,
MPI_COMM_WORLD);
} else { /* my_rank = 1 */
MPI_Recv(&(A[0][2]), 1, column_mpi_t, 0, 0,
MPI_COMM_WORLD, &status);
for (i = 0; i < 10; i++)
printf("%3.1f ", A[i][2]);
printf("\n");
}

MPI_Finalize();
} /* main */