Files

69 lines
2.0 KiB
C

#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#define NRA 64 /* number of rows in matrix A */
#define NCA 64 /* number of columns in matrix A */
#define NCB 64 /* number of columns in matrix B */
int main ()
{
int tid, nthreads, i, j, k, chunk;
double a[NRA][NCA], /* matrix A to be multiplied */
b[NCA][NCB], /* matrix B to be multiplied */
c[NRA][NCB]; /* result matrix C */
chunk = 10; /* set loop iteration chunk size */
/*** Spawn a parallel region explicitly scoping all variables ***/
omp_set_num_threads(4);
#pragma omp parallel shared(a,b,c,nthreads,chunk) private(tid,i,j,k)
{
tid = omp_get_thread_num();
if (tid == 0)
{
nthreads = omp_get_num_threads();
printf("Starting matrix multiple example with %d threads\n",nthreads);
printf("Initializing matrices...\n");
}
/*** Initialize matrices ***/
#pragma omp for schedule (static, chunk)
for (i=0; i<NRA; i++)
for (j=0; j<NCA; j++)
a[i][j]= i+j;
#pragma omp for schedule (static, chunk)
for (i=0; i<NCA; i++)
for (j=0; j<NCB; j++)
b[i][j]= i*j;
#pragma omp for schedule (static, chunk)
for (i=0; i<NRA; i++)
for (j=0; j<NCB; j++)
c[i][j]= 0;
/*** Do matrix multiply sharing iterations on outer loop ***/
/*** Display who does which iterations for demonstration purposes ***/
printf("Thread %d starting matrix multiply...\n",tid);
#pragma omp for schedule (static, chunk)
for (i=0; i<NRA; i++)
{
printf("Thread=%d did row=%d\n",tid,i);
for(j=0; j<NCB; j++)
for (k=0; k<NCA; k++)
c[i][j] += a[i][k] * b[k][j];
}
} /*** End of parallel region ***/
/*** Print results ***/
printf("******************************************************\n");
printf("Result Matrix:\n");
for (i=0; i<NRA; i++)
{
for (j=0; j<NCB; j++)
printf("%6.2f ", c[i][j]);
printf("\n");
}
printf("******************************************************\n");
printf ("Done.\n");
return 0;
}