Solution

void Parallel_matrix_vector_prod(

LOCAL_MATRIX_T local_A /* in */,

int m /* in */,

int n /* in */,

float local_x[] /* in */,

float global_x[] /* in */,

float local_y[] /* out */,

int local_m /* in */,

int local_n /* in */) {

/* local_m = m/p, local_n = n/p */

int i, j;

MPI_Allgather(local_x, local_n, MPI_FLOAT,

global_x, local_n, MPI_FLOAT,

MPI_COMM_WORLD);

for (i = 0; i < local_m; i++) {

local_y[i] = 0.0;

for (j = 0; j < n; j++)

local_y[i] = local_y[i] +

local_A[i][j]*global_x[j];

}

} /* Parallel_matrix_vector_prod */

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