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/******************************************************************************
* * MPI Matrix Multiply - C Version
* * FILE: mpi_mm.c
* * OTHER FILES: make.mpi_mm.c
* * DESCRIPTION:
* * In this code, the master task distributes a matrix multiply
* * operation to numtasks-1 worker tasks.
* * NOTE1: C and Fortran versions of this code differ because of the way
* * arrays are stored/passed. C arrays are row-major order but Fortran
* * arrays are column-major order.
* * AUTHOR: Ros Leibensperger / Blaise Barney
* * CONVERTED TO MPI: George L. Gusciora (1/25/95)
* ******************************************************************************/
#include "mpi.h"
#include <stdio.h>
#define NRA 62 /* number of rows in matrix A */
#define NCA 15 /* number of columns in matrix A */
#define NCB 7 /* number of columns in matrix B */
#define MASTER 0 /* taskid of first task */
#define FROM_MASTER 1 /* setting a message type */
#define FROM_WORKER 2 /* setting a message type */
int main(argc,argv)
int argc;
char *argv[];
{
int numtasks, /* number of tasks in partition */
taskid, /* a task identifier */
numworkers, /* number of worker tasks */
source, /* task id of message source */
dest, /* task id of message destination */
nbytes, /* number of bytes in message */
mtype, /* message type */
rows, /* rows of matrix A sent to each worker */
averow, extra, offset,
/* used to determine rows sent to each worker */
i, j, k, rc; /* misc */
double a[NRA][NCA], /* matrix A to be multiplied */
b[NCA][NCB], /* matrix B to be multiplied */
c[NRA][NCB]; /* result matrix C */
MPI_Status status;
rc = MPI_Init(&argc,&argv);
rc|= MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
rc|= MPI_Comm_rank(MPI_COMM_WORLD,&taskid);
if (rc != 0)
printf ("error initializing MPI and obtaining task ID information\n");
else
printf ("mpi_pi_mm MPI task ID = %d\n", taskid);
numworkers = numtasks-1;
/**************************** master task ************************************/
if (taskid == MASTER)
{
printf("Number of worker tasks = %d\n",numworkers);
for (i=0; i<NRA; i++)
for (j=0; j<NCA; j++)
a[i][j]= i+j;
for (i=0; i<NCA; i++)
for (j=0; j<NCB; j++)
b[i][j]= i*j;
/* send matrix data to the worker tasks */
averow = NRA/numworkers;
extra = NRA%numworkers;
offset = 0;
mtype = FROM_MASTER;
for (dest=1; dest<=numworkers; dest++)
{
rows = (dest <= extra) ? averow+1 : averow;
printf(" sending %d rows to task %d\n",rows,dest);
MPI_Send(&offset, 1, MPI_INT, dest, mtype, MPI_COMM_WORLD);
MPI_Send(&rows, 1, MPI_INT, dest, mtype, MPI_COMM_WORLD);
MPI_Send(&a[offset][0], rows*NCA, MPI_DOUBLE, dest, mtype,
MPI_COMM_WORLD);
MPI_Send(&b, NCA*NCB, MPI_DOUBLE, dest, mtype, MPI_COMM_WORLD);
offset = offset + rows;
}
/* wait for results from all worker tasks */
mtype = FROM_WORKER;
for (i=1; i<=numworkers; i++)
{
source = i;
MPI_Recv(&offset, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&rows, 1, MPI_INT, source, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&c[offset][0], rows*NCB, MPI_DOUBLE, source, mtype, MPI_COMM_WORLD, &status);
}
/* print results */
printf("Here is the result matrix\n");
for (i=0; i<NRA; i++)
{
printf("\n");
for (j=0; j<NCB; j++)
printf("%6.2f ", c[i][j]);
}
printf ("\n");
}
/**************************** worker task ************************************/
if (taskid > MASTER)
{
mtype = FROM_MASTER;
MPI_Recv(&offset, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&rows, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&a, rows*NCA, MPI_DOUBLE, MASTER, mtype, MPI_COMM_WORLD, &status);
MPI_Recv(&b, NCA*NCB, MPI_DOUBLE, MASTER, mtype, MPI_COMM_WORLD, &status);
for (k=0; k<NCB; k++)
for (i=0; i<rows; i++)
{
c[i][k] = 0.0;
for (j=0; j<NCA; j++)
c[i][k] = c[i][k] + a[i][j] * b[j][k];
}
mtype = FROM_WORKER;
MPI_Send(&offset, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD);
MPI_Send(&rows, 1, MPI_INT, MASTER, mtype, MPI_COMM_WORLD);
MPI_Send(&c, rows*NCB, MPI_DOUBLE, MASTER, mtype, MPI_COMM_WORLD);
}
MPI_Finalize();
}