我为分配创建了一个矩阵重数代码,但无法使该函数正常工作,所以我怀疑这是 BLAS 库未正确链接。 在 OS X 中,BLAS 已内置到 Accelerate Framework 中,因此在 makefile 中我通过
-framework Accelerate
链接了库,在 cpp 中我还通过 #include<Accelerate/Accelerate.h>
包含了标头
编译过程中,我的错误是:
Undefined symbols for architecture x86_64:
"dgemm_(char*, char*, int*, int*, int*, double*, double*, int*, double*, int*, double*, double*, int*)"
所以我创建了一个简单的测试代码,但在编译过程中仍然出现错误:
test_2.cpp:35:3: error: use of undeclared identifier 'dgemm_'
dgemm_(&TRANSA, &TRANSB, &M, &N, &K, &ALPHA, A, &LDA, B, &LDB, &BETA, ...
^
1 error generated.
我的简单测试代码是用
编译的 clang++ -o test_2.exe test_2.cpp -framework Accelerate
我的简单代码是:
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <cfloat>
#include <cmath>
#include <sys/time.h>
#ifdef __APPLE__
#include <Accelerate/Accelerate.h>
#else
#include <cblas.h>
#endif
using namespace std;
int main( int argc, char **argv )
{
int n=10;
int N=n;
double *A = (double*) malloc( n * n * sizeof(double) );
double *B = (double*) malloc( n * n * sizeof(double) );
double *C = (double*) malloc( n * n * sizeof(double) );
char TRANSA = 'N';
char TRANSB = 'N';
int M = N;
int K = N;
double ALPHA = 1.;
double BETA = 0.;
int LDA = N;
int LDB = N;
int LDC = N;
dgemm_(&TRANSA, &TRANSB, &M, &N, &K, &ALPHA, A, &LDA, B, &LDB, &BETA, C, &LDC);
return 0;
}
根据文档,Accelerate.framework 为所有 BLAS 函数添加前缀
cblas_
。例如,dgemm
函数被声明为
void cblas_dgemm(const enum CBLAS_ORDER ORDER, const enum CBLAS_TRANSPOSE TRANSA, const enum CBLAS_TRANSPOSE TRANSB, const __LAPACK_int M, const __LAPACK_int N, const __LAPACK_int K, const double ALPHA, const double *A, const __LAPACK_int LDA, const double *B, const __LAPACK_int LDB, const double BETA, double *C, const __LAPACK_int LDC);