omp_matrix_multiply.c

C代码。共享式存储多线程并行计算矩阵相乘代码。适合于SMP结构和多核。

#define NRA 1000 		/* number of rows in matrix A */
#define NCA 1000        	/* number of columns in matrix A */
#define NCB 1000		/* number of columns in matrix B */
main()
{
int    i, j, k;			/* misc */
double a[NRA][NCA], 		/* matrix A to be multiplied */
       b[NCA][NCB],      	/* matrix B to be multiplied */
       c[NRA][NCB];		/* result matrix C */

/* Initialize A, B, and C matrices */
   for (i=0; i< NRA; i++)
      for (j=0; j< NCA; j++)
         a[i][j]= 1.;
   for (i=0; i< NCA; i++)
      for (j=0; j< NCB; j++)
         b[i][j]= 1.;
   for(i=0;i< NRA;i++)
      for(j=0;j< NCB;j++)
         c[i][j] = 0.0;

/* Perform matrix multiply */
#pragma omp parallel shared(a,b,c) private(i,j,k)num_threads(10)
{
#pragma omp for nowait
   for(i=0;i< NRA;i++)
      for(j=0;j< NCB;j++)
         for(k=0;k< NCA;k++)
            c[i][j]+= a[i][k] * b[k][j];
}

   printf("Done\n");
   printf("%f\n ", c[0][0]);
   printf("%f\n ", c[NRA-1][NCB-1]);
   printf ("\n");
}