MKL库矩阵乘法
作者:互联网
此示例是利用Intel 的MKL库函数计算矩阵的乘法,目标为:\(C=\alpha*A*B+\beta*C\),由函数cblas_dgemm实现;
其中\(A\)为\(m\times k\)维矩阵,\(B\)为\(k\times n\)维矩阵,\(C\)为\(m\times n\)维矩阵。
1 cblas_dgemm参数详解
fun cblas_dgemm(Layout, //指定行优先(CblasRowMajor,C)或列优先(CblasColMajor,Fortran)数据排序
TransA, //指定是否转置矩阵A
TransB, //指定是否转置矩阵B
M, //矩阵A和C的行数
N, //矩阵B和C的列数
K, //矩阵A的列,B的行
alpha, //矩阵A和B乘积的比例因子
A, //A矩阵
lda, //矩阵A的第一维的大小
B, //B矩阵
ldb, //矩阵B的第一维的大小
beta, //矩阵C的比例因子
C, //(input/output) 矩阵C
ldc //矩阵C的第一维的大小
)
cblas_dgemm矩阵乘法默认的算法就是\(C=\alpha*A*B+\beta*C\),若只需矩阵\(A\)与\(B\)的乘积,设置\(\alpha=1,\beta=0\)即可。
2 定义待处理矩阵
#include <stdio.h>
#include <stdlib.h>
#include "mkl.h" // 调用mkl头文件
#define min(x,y) (((x) < (y)) ? (x) : (y))
double* A, * B, * C; //声明三个矩阵变量,并分配内存
int m, n, k, i, j; //声明矩阵的维度,其中
double alpha, beta;
m = 2000, k = 200, n = 1000;
alpha = 1.0; beta = 0.0;
A = (double*)mkl_malloc(m * k * sizeof(double), 64); //按照矩阵维度分配内存
B = (double*)mkl_malloc(k * n * sizeof(double), 64); //mkl_malloc用法与malloc相似,64表示64位
C = (double*)mkl_malloc(m * n * sizeof(double), 64);
if (A == NULL || B == NULL || C == NULL) { //判空
mkl_free(A);
mkl_free(B);
mkl_free(C);
return 1;
}
for (i = 0; i < (m * k); i++) { //赋值
A[i] = (double)(i + 1);
}
for (i = 0; i < (k * n); i++) {
B[i] = (double)(-i - 1);
}
for (i = 0; i < (m * n); i++) {
C[i] = 0.0;
}
其中\(A\)和\(B\)矩阵设置为:
\[\begin{array}{l} A = \left[ {\begin{array}{*{20}{c}} {1.0}&{2.0}& \cdots &{1000.0}\\ {1001.0}&{1002.0}& \cdots &{2000.0}\\ \vdots & \vdots & \ddots & \cdots \\ {999001.0}&{999002.0}& \cdots &{1000000.0} \end{array}} \right] \space B = \left[ {\begin{array}{*{20}{c}} {-1.0}&{-2.0}& \cdots &{-1000.0}\\ {-1001.0}&{-1002.0}& \cdots &{-2000.0}\\ \vdots & \vdots & \ddots & \cdots \\ {-999001.0}&{-999002.0}& \cdots &{-1000000.0} \end{array}} \right] \end{array} \]\(C\)矩阵为全0。
3 执行矩阵乘法
回到例子中,对照上面的参数,将C矩阵用A与B的矩阵乘法表示:
cblas_dgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans,
m, n, k, alpha, A, k, B, n, beta, C, n);
//在执行完成后,释放内存
mkl_free(A);
mkl_free(B);
mkl_free(C);
执行后的得到结果如下:
完整代码
#include <stdio.h>
#include <stdlib.h>
#include "mkl.h"
#define min(x,y) (((x) < (y)) ? (x) : (y))
int main()
{
double* A, * B, * C;
int m, n, k, i, j;
double alpha, beta;
m = 2000, k = 200, n = 1000;
alpha = 1.0; beta = 0.0;
A = (double*)mkl_malloc(m * k * sizeof(double), 64);
B = (double*)mkl_malloc(k * n * sizeof(double), 64);
C = (double*)mkl_malloc(m * n * sizeof(double), 64);
if (A == NULL || B == NULL || C == NULL) {
mkl_free(A);
mkl_free(B);
mkl_free(C);
return 1;
}
for (i = 0; i < (m * k); i++) {
A[i] = (double)(i + 1);
}
for (i = 0; i < (k * n); i++) {
B[i] = (double)(-i - 1);
}
for (i = 0; i < (m * n); i++) {
C[i] = 0.0;
}
cblas_dgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans,
m, n, k, alpha, A, k, B, n, beta, C, n);
for (i = 0; i < min(m, 6); i++) {
for (j = 0; j < min(k, 6); j++) {
printf("%12.0f", A[j + i * k]);
}
printf("\n");
}
for (i = 0; i < min(k, 6); i++) {
for (j = 0; j < min(n, 6); j++) {
printf("%12.0f", B[j + i * n]);
}
printf("\n");
}
for (i = 0; i < min(m, 6); i++) {
for (j = 0; j < min(n, 6); j++) {
printf("%12.5G", C[j + i * n]);
}
printf("\n");
}
mkl_free(A);
mkl_free(B);
mkl_free(C);
return 0;
}
标签:MKL,++,double,mkl,矩阵,free,beta,乘法 来源: https://www.cnblogs.com/GeophysicsWorker/p/16175589.html