Hi,
Is there a way to send a 2-D array at once instead of send one row by one
row? I wrote a code with 2 processors, processor 0 generates 2-D array and
send half of the rows to processor 1. I tested with 2x2 array, the result is
fine. But when I tested with 4x4 array. The last two numbers received in
processor 1 are 0.
I attach the code as following:
#include <stdio.h>
#include "mpi.h"
#include <stdlib.h>
#include <math.h>
#include <time.h>
int main(int argc, char *argv[]) {
int rank; /* Rank of process */
int size; /* Number of processes */
int source; /* Rank of sender */
int dest; /* Rank of receiver */
int tag = 51; /* Tag for messages */
int m,n,g;
int distr,cust;
int **in_set;
/*int in_set[20][20];*/
int sum,sum1;
int **R;
/*int R[20][20]*/
int x,y,xx,yy,z;
int tempx, tempy;
int count;
int x1,y1,xx1,yy1,z1;
int tempx1, tempy1;
MPI_Status status; /* Return status for wait*/
MPI_Request request; /* Return request for send/receive*/
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
srand ( time(NULL) ); /*random seed used originally to get the input
file*/
if (rank==0){
printf("Enter number of rows x = ");
scanf("%d",&n);
while ((n%size) != 0) {
printf("\nNumber of columns should be equally divided among
processors\n");
printf("Please enter a new x: ");
scanf("%d",&n);
}
printf("Enter number of columns y = ");
scanf("%d",&m);
distr = n / size;
in_set = (int **)malloc(n * sizeof(int *));
for(x=0; x < n; x++) {
in_set[x] = (int *)malloc(m * sizeof(int));
}
for (x=0;x<n;x++){
for (y=0;y<m;y++){
in_set[x][y] = 1+ rand()/(((double)RAND_MAX + 1) / 8);
printf("[%d][%d] = %d\n",x,y, in_set[x][y]);
}
}
MPI_Send(&distr, 1, MPI_INT, 1,tag+29, MPI_COMM_WORLD);
MPI_Send(&m, 1, MPI_INT, 1,tag+2, MPI_COMM_WORLD);
MPI_Send(in_set[distr], (distr)*m, MPI_INT, 1,tag, MPI_COMM_WORLD);
}
if (rank!=0) {
MPI_Recv(&distr, 1, MPI_INT, 0, tag+29, MPI_COMM_WORLD, &status);
MPI_Recv(&m, 1, MPI_INT, 0, tag+2, MPI_COMM_WORLD, &status);
R = (int **)malloc((int)distr * sizeof(int *));
for(x1=0; x1<distr; x1++) {
R[x1] = (int *)malloc((int)m * sizeof(int));
}
printf("myid = %d\tdistr = %d m = %d\n",rank, distr, m);
MPI_Recv(*R, (distr)*m, MPI_INT, 0, tag, MPI_COMM_WORLD, &status);
MPI_Get_count(&status, MPI_INT, &count);
printf("count = %d\n", count);
printf("RECEIVED IN %d\n", rank);
for (x1=0;x1<distr;x1++){
for (y1=0;y1<m;y1++){
printf("[%d][%d] = %d", x1, y1, R[x1][y1]);
}
printf("\n");
}
}
MPI_Finalize();
}
The 4x4 array result is:
Enter number of rows x = 4
Enter number of columns y = 4
[0][0] = 2
[0][1] = 1
[0][2] = 7
[0][3] = 7
[1][0] = 5
[1][1] = 3
[1][2] = 7
[1][3] = 3
[2][0] = 4
[2][1] = 2
[2][2] = 1
[2][3] = 8
[3][0] = 5
[3][1] = 1
[3][2] = 6
[3][3] = 3
myid = 1 distr = 2 m = 4
count = 8
RECEIVED IN 1
[0][0] = 4[0][1] = 2[0][2] = 1[0][3] = 8
[1][0] = 5[1][1] = 1[1][2] = 0[1][3] = 0
Best wishes,
Yeliang Zhang
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