[MPICH] help self-defined datatype

[llwaeva at 21cn.com]

Hi all,
  I need you help in self-defined datatype. I have written the following
code

  #include <mpi.h>
  #include <stdio.h>

  #define FIVE

  #define NCOLS 4
  #define NROWS 4

  #ifdef FIVE
    typedef struct
    {
      double r, c, d, v, f;
    } Grid;
  #else
    typedef struct
    {
      double r, c, v, d;
    } Grid;
  #endif

  Grid data[NROWS][NCOLS];

  int myrank, NODENUM;
  int SIZE;

  MPI_Datatype GRID;
  MPI_Datatype ROW;


  void initialize(int argc, char **argv)
  { int errcode, i, j;
    #ifndef FIVE
      int S=4;
      MPI_Datatype type[4] = { MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE};
      int blocklen[4] = { 1, 1, 1, 1 };
      MPI_Aint disp[4] = { 0, sizeof(double), sizeof(double), sizeof(double)};
    #else
      int S=5;
      MPI_Datatype type[5] = { MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE, MPI_DOUBLE};
      int blocklen[5] = { 1, 1, 1, 1, 1 };
      MPI_Aint disp[5] = { 0, sizeof(double), sizeof(double), sizeof(double), sizeof(double)};
    #endif

    errcode = MPI_Init(&argc, &argv);
    if (errcode == MPI_SUCCESS)
    {
      MPI_Comm_rank( MPI_COMM_WORLD, &myrank );
      MPI_Comm_size( MPI_COMM_WORLD, &NODENUM );

      SIZE = NROWS/NODENUM;

      MPI_Type_struct( S, blocklen, disp, type, &GRID );
      MPI_Type_commit( &GRID );

      MPI_Type_vector( NCOLS, 1, 1, GRID, &ROW );
      MPI_Type_commit( &ROW );

      for (i=0; i<NROWS; i++)
      {
        for (j=0; j<NCOLS; j++)
        {
          data[i][j].r = (double)(i+1);
          data[i][j].c = (double)(j+1);
          data[i][j].d = 1.0;
          data[i][j].v = (double)(i*NCOLS + j + 1);
          #ifdef FIVE
            data[i][j].f = 2.0;
          #endif
        }
      }
    }
  }


  void finalize(void)
  {
    MPI_Type_free(&GRID);
    MPI_Type_free(&ROW);
    MPI_Finalize();
  }

  int main(int argc, char *argv[])
  {
    initialize(argc, argv);

    MPI_Barrier( MPI_COMM_WORLD );
    /* show data here */

    if (myrank==0)
    {
      MPI_Send( &data[0][0], 1, ROW, 1, 22, MPI_COMM_WORLD );
    }
    else MPI_Recv( &data[SIZE][0], 1, ROW, 0, 22, MPI_COMM_WORLD, MPI_STATUS_IGNORE );

    MPI_Barrier( MPI_COMM_WORLD );
    /* show data here */

    finalize();
    return 0;
  }

The program is running over two computers. At the beginning, each
computer holds all the data stored in 'data' array. I am going to define
a new datatype for a row and send the first row of the array from node 0
to node 1. However, the result is not that I wanted. I print the whole
array at node 1

The original array is

 1  2  3  4 
 5  6  7  8 
 9 10  11 12 
13 14  15 16 


if macro 'FIVE' is defined, i.e. five data defined in the struct, I got

 1  2   3  4 
 5  6   7  8 
 1 10  11 12 
13 14  15 16 

if macro 'FIVE' is undefine, i.e. only four data defined in the struct,
I got

 1  2   3  4 
 5  6   7  8 
 1  2  11 12 
13 14  15 16 

But I an intending to get

 1  2   3  4 
 5  6   7  8 
 1  2   3  4  <-----  a row received from the first row on node 0
13 14  15 16