#include "mpi.h"int main( int argc, char *argv[] ){    int          gsizes[2], distribs[2], dargs[2], psizes[2], rank, size, m, n;    MPI_Datatype filetype;    int          local_array_size, num_local_rows, num_local_cols;    int          row_procs, col_procs, row_rank, col_rank;    MPI_File     fh;     float        *local_array;     MPI_Status   status;    MPI_Init( &argc, &argv );    /* ... */    /* This code is particular to a 2 x 3 process decomposition */    MPI_Comm_size( MPI_COMM_WORLD, &size );    if (size != 6) {	printf( "Communicator size must be 6\n" );	MPI_Abort( MPI_COMM_WORLD, 1 );    }    /* See comments on block distribution */    row_procs = 2;    col_procs = 3;    num_local_rows = (m + row_procs - 1) / row_procs;    /* adjust for last row */    if (row_rank == row_procs-1) 	num_local_rows = m - (row_procs-1) * num_local_rows;    num_local_cols = (n + col_procs - 1) / col_procs;    /* adjust for last column */    if (col_rank == col_procs-1) 	num_local_cols = n - (col_procs-1) * num_local_cols;    local_array = (float *)malloc( num_local_rows * num_local_cols * sizeof(float) );    /* ... set elements of local_array ... */    gsizes[0] = m;    /* no. of rows in global array */    gsizes[1] = n;    /* no. of columns in global array*/    distribs[0] = MPI_DISTRIBUTE_BLOCK;  /* block distribution */    distribs[1] = MPI_DISTRIBUTE_BLOCK;  /* block distribution */    dargs[0] = MPI_DISTRIBUTE_DFLT_DARG; /* default block size */    dargs[1] = MPI_DISTRIBUTE_DFLT_DARG; /* default block size */    psizes[0] = row_procs;  /* no. of processes in vertical dimension 			       of process grid */    psizes[1] = col_procs;  /* no. of processes in horizontal dimension 			       of process grid */    MPI_Comm_rank(MPI_COMM_WORLD, &rank);    MPI_Type_create_darray(6, rank, 2, gsizes, distribs, dargs, 			   psizes, MPI_ORDER_C, MPI_FLOAT, &filetype);    MPI_Type_commit(&filetype);        MPI_File_open(MPI_COMM_WORLD, "/pfs/datafile", 		  MPI_MODE_CREATE | MPI_MODE_WRONLY, 		  MPI_INFO_NULL, &fh);    MPI_File_set_view(fh, 0, MPI_FLOAT, filetype, "native", 		      MPI_INFO_NULL);    local_array_size = num_local_rows * num_local_cols;    MPI_File_write_all(fh, local_array, local_array_size, 		       MPI_FLOAT, &status);        MPI_File_close(&fh);    /* ... */    MPI_Finalize();    return 0;}