Question

我正在用C ++编写一个使用CLAPACK ATLAS库的程序。但是，我无法让程序成功链接到库。我写了一个小C程序来更好地演示问题。有趣的是，如果我用GCC编译它，这个小的演示程序链接就好了，但是当我尝试用G ++编译时，我得到了相同的链接器错误。我希望有人可以帮我弄清楚G ++和GCC究竟在做什么，以便将原始程序链接起来（原始程序是一个C ++程序而我不能只是“使用GCC”）

以下是小型演示程序：

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <cblas.h>
#include <clapack.h>

// a is a column-major array of all the values in the matrix to invert
// The matrix's height and width are the same because it is a square matrix.
void invertMatrix(float *a, unsigned int height)
{
    int info, ipiv[height];
    info = clapack_sgetrf(CblasColMajor, height, height, a, height, ipiv);
    info = clapack_sgetri(CblasColMajor, height, a, height, ipiv);
}

void displayMatrix(float *a, unsigned int height, unsigned int width)
{
    int i, j;
    for(i = 0; i < height; i++)
    {
            for(j = 0; j < width; j++)
            {
                    printf("%1.3f ", a[height*j + i]);
            }
            printf("\n");
    }
    printf("\n");
}

void multiplyMatrix(float *a, unsigned int aheight, unsigned int awidth, float *b, unsigned int bwidth, float *c)
{
    cblas_sgemm(CblasColMajor, CblasNoTrans, CblasNoTrans, aheight, bwidth, awidth, 1.0f, a, aheight, b, awidth, 0.0f, c, aheight);
}

int main(int argc, char *argv[])
{
    int i;
    float a[9], b[9], c[9];
    srand(time(NULL));
    for(i = 0; i < 9; i++)
    {
            a[i] = 1.0f*rand()/RAND_MAX;
            b[i] = a[i];
    }
    displayMatrix(a, 3, 3);
    invertMatrix(a, 3);
    multiplyMatrix(a, 3, 3, b, 3, c);
    displayMatrix(c, 3, 3);
    return 0;
}

当我尝试用GCC编译它时，它的工作正常：

$ gcc -o linearalgebra linearalgebra.c -I /usr/include/atlas -L /usr/lib64/atlas/ -llapack -lblas
$ ./linearalgebra
0.723 0.755 0.753
0.179 0.912 0.349
0.642 0.265 0.530

1.000 -0.000 0.000
0.000 1.000 0.000
0.000 0.000 1.000

$

当我尝试用G ++编译它时，它会给链接器错误：

$ g++ -o linearalgebra linearalgebra.c -I /usr/include/atlas -L /usr/lib64/atlas/ -llapack -lblas
/tmp/ccuhmDKE.o: In function `multiplyMatrix(float*, unsigned int, unsigned int, float*, unsigned int, float*)':
linearalgebra.c:(.text+0x7b): undefined reference to `cblas_sgemm(CBLAS_ORDER, CBLAS_TRANSPOSE, CBLAS_TRANSPOSE, int, int, int, float, float const*, int, float const*, int, float, float*, int)'
/tmp/ccuhmDKE.o: In function `invertMatrix(float*, unsigned int)':
linearalgebra.c:(.text+0x182): undefined reference to `clapack_sgetrf(CBLAS_ORDER, int, int, float*, int, int*)'
linearalgebra.c:(.text+0x1a0): undefined reference to `clapack_sgetri(CBLAS_ORDER, int, float*, int, int const*)'
collect2: ld returned 1 exit status
$

最后但并非最不重要：有关我的系统的一些信息：
操作系统：Fedora 10 (Linux hostname 2.6.27.25-170.2.72.fc10.x86_64 #1 SMP Sun Jun 21 18:39:34 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux)
库：

$ yum list | grep lapack
lapack.x86_64                        3.1.1-4.fc10                 installed
lapack-debuginfo.x86_64              3.1.1-4.fc10                 installed
lapack-devel.x86_64                  3.1.1-4.fc10                 @fedora
$ yum list | grep blas
blas.x86_64                          3.1.1-4.fc10                 installed
blas-devel.x86_64                    3.1.1-4.fc10                 installed
$ yum list | grep atlas
atlas.x86_64                         3.6.0-15.fc10                installed
atlas-debuginfo.x86_64               3.6.0-15.fc10                installed
atlas-devel.x86_64                   3.6.0-15.fc10                @fedora

另外，对于奖励积分：LAPACK和ATLAS之间的历史和功能关系究竟是什么？

Answer 1

如果要将C ++程序链接到C库，则必须确保C库中的所有函数等都以extern "C"为前缀。 C ++编译器破坏了C ++符号名称，这使得链接器无法将符号与C库中的名称进行匹配。您可以使用块来声明C符号：

extern "C" {
  ...
}

您可以定义预处理程序符号，以指示cblas.h和clapack.h在所有声明前包含必要的extern "C"。

C C ++链接错误

1 个答案: