L11Ex5.cpp

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

#define INCLUDE_DIAGONAL 1
#define lower_triangle_size_with_diagonal(m_size) (m_size * m_size - m_size) / 2 + m_size
#define lower_triangle_size_without_diagonal(m_size) (m_size * m_size - m_size) / 2
#define lower_tiangle_size(m_size) INCLUDE_DIAGONAL ? lower_triangle_size_with_diagonal(m_size) : lower_triangle_size_without_diagonal(m_size)

void printMatrix(int *matrix, int size) {
	for (int i = 0; i < size; i++) {
		for (int j = 0; j < size; j++) {
			printf("%5d", matrix[i * size + j]);
		}
		printf("\n");
	}
}

int main(int argc, char* argv[])
{
    int size, myrank;
    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &myrank);

	int m_size;
	int *matrixA, *matrixB;

	if (myrank == 0) {
		printf("Input matrix size:\n");
		scanf("%d", &m_size);

		matrixA = (int*)malloc(m_size * m_size * sizeof(int));
		matrixB = (int*)malloc(m_size * m_size * sizeof(int));
		for (int i = 0; i < m_size * m_size; i++) {
			matrixA[i] = i;
			matrixB[i] = -i;
		}
		
		printf("== A ==\n");
		printMatrix(matrixA, m_size);
		printf("== B ==\n");
		printMatrix(matrixB, m_size);

		int lengths[m_size], displacements[m_size];
		for (int i = 0; i < m_size; i++) {
			lengths[i] = INCLUDE_DIAGONAL ? i + 1 : i;
			displacements[i] = i*m_size;
		}
		
		MPI_Datatype lower_triangle_type;
		MPI_Type_indexed(m_size, lengths, displacements, MPI_INT, &lower_triangle_type);
		MPI_Type_commit(&lower_triangle_type);

		MPI_Send(matrixA, 1, lower_triangle_type, 0, 111, MPI_COMM_WORLD);
		MPI_Recv(matrixB, 1, lower_triangle_type, 0, 111, MPI_COMM_WORLD, MPI_STATUS_IGNORE);

		printf("== A ==\n");
		printMatrix(matrixA, m_size);
		printf("== B ==\n");
		printMatrix(matrixB, m_size);
	}
	
    MPI_Finalize();
 
    return 0;
}