openmp实现矩阵乘法
时间: 2023-11-17 12:07:52 浏览: 40
好的,下面是使用OpenMP实现矩阵乘法的示例代码:
```c++
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#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 */
int main (int argc, char *argv[])
{
int tid, nthreads, i, j, k;
double a[NRA][NCA], /* matrix A to be multiplied */
b[NCA][NCB], /* matrix B to be multiplied */
c[NRA][NCB]; /* result matrix C */
/* Initialize matrices */
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;
for (i=0; i<NRA; i++)
for (j=0; j<NCB; j++)
c[i][j]= 0;
/* Perform matrix multiplication with OpenMP */
#pragma omp parallel shared(a,b,c) private(tid,i,j,k)
{
tid = omp_get_thread_num();
if (tid == 0)
{
nthreads = omp_get_num_threads();
printf("Starting matrix multiplication with %d threads\n",nthreads);
}
#pragma omp for schedule(static)
for (i=0; i<NRA; i++)
{
printf("Thread %d starting 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];
}
}
/* 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");
}
```
这个示例代码中,我们使用了OpenMP的并行化技术来加速矩阵乘法的计算。在主函数中,我们首先定义了三个矩阵a、b和c,然后对矩阵a和b进行了初始化。接着,我们使用OpenMP的#pragma omp parallel指令来创建一个并行区域,其中shared(a,b,c)表示a、b和c是共享变量,private(tid,i,j,k)表示tid、i、j和k是私有变量。在并行区域中,我们使用#pragma omp for指令来并行化矩阵乘法的计算,其中schedule(static)表示采用静态调度方式。最后,我们输出了计算结果。