C语言中LAPACKE dgels_uu的分段错误

我想用C中的LAPACK's dgels解决最小二乘问题| Ax-b |->min，但我得到了一个分段错误（我知道有，但代码完全不同，答案不适用于我的问题）。 我已经找到了问题所在，执行dgels_uu时它是正确的

代码：

---

然后我尝试查找一个示例程序，发现（使用sgesv，但我认为它可能与DGEL类似）。在将dgels_uUa（transa，m，n，nrhs，A，lda，b，ldb，work，0，info）重写为dgels_Ua（&transa，&m，&n，&nrhs，A，&lda，b，&ldb，work，0，&info）之后，没有更多的错误消息，因此我认为这是正确的方法。

0

对于参数

lwork

来说不是合法的值。实际上，它必须是指向c中整数的指针，因为在fortran中所有参数都是通过引用调用的，而在c中所有参数都是通过值调用的。此外，

lwork

的值指定数组

work

的长度，该数组：

lwork>=max（1，MN+max（MN，NRHS））

。唯一的例外是

lwork=-1

：在这种特殊情况下，函数返回到

work[0]

中数组

work

的最佳大小

例如，可以尝试以下行：

    lapack_int lwork=n;
    if (m<n){lwork=m;}
    lwork=-1;
    double query;
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, &query, &lwork, &info);
    lwork=(int)query;
    printf("the optimal size is %d \n",lwork);
    work=malloc(lwork*sizeof(double));
    if(work==NULL){fprintf(stderr,"maloc failed\n");exit(1);}
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, work, &lwork, &info);
    printf("test 2 \n");

    printf("%g %g %g\n",b[0],b[1],b[2]);

---

请参阅中的文档，然后向下滚动至DGEL。看起来你用很多指针来调用它，这些指针的值就足够了。另外，打开编译器的警告，这样如果你用错误类型的参数调用它，它就会抱怨。至于样式：预处理器宏通常是大写的，这样你就不会把它们和宏混淆了。因此，对于

#定义列3

而不是使用

#定义列3

使用调试器，并在segfault发生后检查

dgels

的参数值。@PaulOgilvie:是的，警告已打开，但gcc没有告诉我任何警告。事实上，我以前试着用值来编译它，也就是说，使用dgels（transa，m，n，nrhs，A，lda，b，ldb，work，0，info）。然而，随后我收到了很多错误消息（见编辑后的原始帖子）。@PaulOgilvie:我尝试了LAPACK_dgels（LAPACK_COL_MAJOR，transa，m，n，nrhs，A，lda，b，ldb），而不是您链接的文档中显示的dgels（LAPACK_COL_MAJOR，transa，m，n，nrhs，A，lda，b，ldb）。它编译时没有警告，也没有分段错误。但是，它仍然不能正常工作，这是一个不同的问题。非常感谢您的详细解释和正确的代码，它解决了我最初使用dgels_uu的问题和我使用LAPACK_dgel的问题。

lapack_error.c: In function ‘main’:
lapack_error.c:32:13: warning: passing argument 1 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
             ^~~~~~
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘char *’ but argument is of type ‘char’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:21: warning: passing argument 2 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                     ^
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:24: warning: passing argument 3 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                        ^
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:27: warning: passing argument 4 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                           ^~~~
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:36: warning: passing argument 6 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                                    ^~~
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:44: warning: passing argument 8 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                                        ^~~
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,
      ^
lapack_error.c:32:58: warning: passing argument 11 of ‘dgels_’ makes pointer from integer without a cast [-Wint-conversion]
      dgels_(transa, m, n, nrhs, A, lda, b, ldb, work, 0, info);
                                                          ^~~~
In file included from /usr/include/lapacke.h:143:0,
                 from lapack_error.c:2:
/usr/include/lapacke.h:14793:6: note: expected ‘int *’ but argument is of type ‘int’
 void LAPACK_dgels( char* trans, lapack_int* m, lapack_int* n, lapack_int* nrhs,

    lapack_int lwork=n;
    if (m<n){lwork=m;}
    lwork=-1;
    double query;
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, &query, &lwork, &info);
    lwork=(int)query;
    printf("the optimal size is %d \n",lwork);
    work=malloc(lwork*sizeof(double));
    if(work==NULL){fprintf(stderr,"maloc failed\n");exit(1);}
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, work, &lwork, &info);
    printf("test 2 \n");

    printf("%g %g %g\n",b[0],b[1],b[2]);

#include <stdio.h>
#include <lapacke.h>

#define COL 3               
#define ROW 4

int main()
{
    char transa ='N';
    lapack_int m, n, nrhs, lda, ldb, info;
    m=ROW;
    n=COL; 
    nrhs=1;
    lda=ROW;
    ldb=ROW;
    double* work;

    double A [COL*ROW] = 
    { 1.1, 4.2, 1.7, 2.5,
    2.1, 2.8, 3.4, 4.2, 
    8.5, 4.4, 5.2, 7.8 };

    double b[ROW] = 
    { 39.3,         
    27.4,         
    29.3,         
    42.1 };

    printf("test 1 \n");
    lapack_int lwork=n;
    if (m<n){lwork=m;}
    lwork=-1;
    double query;
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, &query, &lwork, &info);
    lwork=(int)query;
    printf("the optimal size is %d \n",lwork);
    work=malloc(lwork*sizeof(double));
    if(work==NULL){fprintf(stderr,"maloc failed\n");exit(1);}
    dgels_(&transa, &m, &n, &nrhs, A, &lda, b, &ldb, work, &lwork, &info);
    printf("test 2 \n");

    printf("%g %g %g\n",b[0],b[1],b[2]);


    free(work);

    double Aa [COL*ROW] = 
    { 1.1, 4.2, 1.7,   2.5,
    2.1, 2.8, 3.4, 4.2, 
    8.5, 4.4, 5.2, 7.8 };

    double bb[ROW] = 
    { 39.3,         
    27.4,         
    29.3,         
    42.1 };

    //with lapacke
    info= LAPACKE_dgels(LAPACK_COL_MAJOR,transa, m, n, nrhs, Aa, lda, bb, ldb);
    printf("%g %g %g\n",bb[0],bb[1],bb[2]);

    //

    double Aaa [COL*ROW] = 
    { 1.1, 4.2, 1.7,   
    2.5, 2.1, 2.8,   
    3.4, 4.2, 8.5,   
    4.4, 5.2, 7.8 };

    double bbb[ROW] = 
    { 16.3,         
    17.9,         
    45.8,         
    46 };

    //with lapacke
    info= LAPACKE_dgels(LAPACK_COL_MAJOR,'T', n, m, nrhs, Aaa, n, bbb, ldb);
    printf("%g %g %g\n",bbb[0],bbb[1],bbb[2]);


    double Aaaa [COL*ROW] = 
    { 1.1, 4.2, 1.7,   
    2.5, 2.1, 2.8,   
    3.4, 4.2, 8.5,   
    4.4, 5.2, 7.8 };

    double bbbb[ROW] = 
    { 16.3,         
    17.9,         
    45.8,         
    46 };

    // it is still possible to allocate the buffer yourself once for all if LAPACKE_dgels_work is used.
    // it can be useful if dgels is used many times, using the same transa, m,n,nrhs,lda,ldb but different A or b.
    info= LAPACKE_dgels_work(LAPACK_COL_MAJOR,'T', n, m, nrhs, Aaaa, n, bbbb, ldb,&query,-1);
    lwork=(int)query;
    printf("the optimal size is %d \n",lwork);
    work=malloc(lwork*sizeof(double));
    if(work==NULL){fprintf(stderr,"maloc failed\n");exit(1);}
    info= LAPACKE_dgels_work(LAPACK_COL_MAJOR,'T', n, m, nrhs, Aaaa, n, bbbb, ldb,work,lwork);
    free(work);
    printf("%g %g %g\n",bbbb[0],bbbb[1],bbbb[2]);

    return 0;
}