gistfile1.txt

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

int main(int argc, char* argv[]){
    int rank, size, i, j, k, tag = 0;

    MPI_Status status;
    MPI_Init(&argc, &argv );
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);

    double start_time,final_time;

    // Set matrices lines and columns
    int lines = 1000;
    int columns = 1000;


    start_time = MPI_Wtime();

    int *matrix_line = malloc(sizeof(int) * lines);


    // initialize the matrix_b
    int** matrix_b = (int**) malloc(sizeof(int*) * lines);
    matrix_b[0] = (int*) malloc(lines * columns * sizeof(int));
    for(i=1; i<lines; i++)
        matrix_b[i] = &(matrix_b[0][i*columns]);

    for(i = 0; i < lines; i++){
        for(j = 0; j < columns; j++){
           matrix_b[i][j] = (int) j;
        }
    }

    // final matrix
    int** final_matrix = (int**) malloc(sizeof(int*) * lines);
    final_matrix[0] = (int*) malloc(lines * columns * sizeof(int));
    for(i=1; i<lines; i++)
        final_matrix[i] = &(final_matrix[0][i*columns]);

    if(size > 1){

        int partial = lines / (size -1);
        printf("PARTIAL: %d", partial);



        int** receive = (int**) malloc(sizeof(int*) * partial);
        receive[0] = (int*) malloc(partial * columns * sizeof(int));
        for(i=1; i<lines; i++)
            receive[i] = &(receive[0][i*columns]);

        int** partial_matrix = (int**) malloc(sizeof(int*) * partial);
        partial_matrix[0] = (int*) malloc(partial * columns * sizeof(int));
        for(i=1; i<lines; i++)
            partial_matrix[i] = &(partial_matrix[0][i*columns]);

        int *line = malloc(sizeof(int) * lines);

        if (rank == 0){

            int** matrix_a = (int**) malloc(sizeof(int*) * lines);
            matrix_a[0] = (int*) malloc(lines * columns * sizeof(int));
            for(i=1; i<lines; i++)
                matrix_a[i] = &(matrix_a[0][i*columns]);

            for(i = 0; i < lines; i++){
                for(j = 0; j < columns; j++){
                   matrix_a[i][j] = (int) j;
                }
            }

            int count = 0;
            for(j = 1; j < size; j++){

                printf("COUNT: %d\n", count);
                MPI_Send(&matrix_a[count][0], partial * columns, MPI_INT, j, tag, MPI_COMM_WORLD);
                MPI_Recv(&final_matrix[count][0], partial * columns, MPI_INT, j, tag, MPI_COMM_WORLD, &status);
                count += partial;

            }

            final_time = MPI_Wtime();
            printf("Time: %f\n", final_time - start_time);

        } else {

            printf("PARTIAL => %d", partial);
            MPI_Recv(&receive[0][0], partial * columns, MPI_INT, 0, tag, MPI_COMM_WORLD, &status);

            int partial_counter = 0.0;
            for(k = 0; k < partial; k++){
                for(i = 0; i < partial; i++){
                    for(j = 0; j < columns; j++){
                        // printf("%d * %d + ", receive[j], matrix_b[j][i]);
                        partial_counter += receive[k][j] * matrix_b[j][i];
                    }
                    // printf("PARTIAL: %d\n", partial);
                    line[i] = partial_counter;
                    partial_counter = 0.0;
                }
                partial_matrix[k] = matrix_line;
            }

            MPI_Send(&partial_matrix[0][0], partial * columns, MPI_INT, 0, tag, MPI_COMM_WORLD);

        }

    } else {

        int** matrix_a = (int**) malloc(sizeof(int*) * lines);
        matrix_a[0] = (int*) malloc(lines * columns * sizeof(int));
        for(i=1; i<lines; i++)
            matrix_a[i] = &(matrix_a[0][i*columns]);

        for(i = 0; i < lines; i++){
            for(j = 0; j < columns; j++){
               matrix_a[i][j] = (int) j;
            }
        }
        int partial = 0.0;
        for(k = 0; k < lines; k++){
            for(i = 0; i < lines; i++){
                for(j = 0; j < columns; j++){
                    // printf("%d * %d + ", receive[j], matrix_b[j][i]);
                    partial += matrix_a[k][j] * matrix_b[j][i];
                }
                // printf("PARTIAL: %d\n", partial);
                matrix_line[i] = partial;
                partial = 0;
            }
            final_matrix[k] = matrix_line;
        }

        final_time = MPI_Wtime();
        printf("Time: %f\n", final_time - start_time);

    }

    MPI_Finalize();
}