/* Copyright 2004 David A. Joiner and the Shodor Education Foundation, Inc.
 *
 * /

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

#define MATRIX_SIZE_MAX 10

int main(int argc,char ** argv) {
    int A[MATRIX_SIZE_MAX][MATRIX_SIZE_MAX];
    int matrix_size=6;
    MPI_Datatype partial_array;
    int rank,size;
    MPI_Status status;

    MPI_Init(&argc,&argv);
    MPI_Comm_rank(MPI_COMM_WORLD,&rank);
    MPI_Comm_size(MPI_COMM_WORLD,&size);
    
    if (size<2) {
        printf("Error, at least 2 processes needed\n");
        exit(0);
    }
    if (matrix_size>MATRIX_SIZE_MAX) {
        printf("Error, matrix is larger than maximum allocation\n");
        exit(0);
    }

    MPI_Type_vector(matrix_size, matrix_size/2,
        MATRIX_SIZE_MAX, MPI_INT, &partial_array);
    /* MPI_Type_vector ( int count, int block_length,
     *     int stride, MPI_Datatype oldtype, MPI_Datatype * newtype);
     *
     * define "count" segments, with "block_length" items per segment,
     * spaced "stride" apart, of type oldtype as newtype */

    MPI_Type_commit(&partial_array);
    /* commit datatype so that it can be used in sends and receives */

    if (rank == 0) {
        int i,j;
        // server - initialize data and send
        for (i = 0; i< matrix_size; i++) {
            for (j=0;j<matrix_size;j++) {
                A[i][j] = i*matrix_size + j;
            }
        }
        MPI_Send(&(A[0][0]), 1, partial_array, 1, 0, MPI_COMM_WORLD);
    } else if (rank==1) {
        int i,j;
        // client - receive data and print
        for (i = 0; i< matrix_size; i++) {
            for (j=0;j<matrix_size;j++) {
                A[i][j] = 0;
            }
        }
        MPI_Recv(&(A[0][0]), 1, partial_array, 0, 0, MPI_COMM_WORLD, &status);
        printf("\t\t");
        for (i =0 ; i<matrix_size;i++) printf("%d\t",i);
        printf("\n");
        printf("\n");
        for (i = 0; i< matrix_size; i++) {
            printf("%d\t\t",i);
            for (j=0;j<matrix_size;j++) {
                printf("%d\t",A[i][j]); 
            }
            printf("\n");
        }
    }

    MPI_Finalize();

}