Blas DGEMV输入误差

Question

我很难弄明白为什么一个blas电话会抛出n个错误。问题电话是最后一个blas电话。代码编译时没有问题，并且运行良好，直到此调用与以下消息一起失败为止。

** ACML错误:在输入DGEMV参数6时有一个非法值

就我所能知道的一切而言，输入类型是正确的，数组a是否正确，我将非常感谢对这个问题的洞察力。谢谢

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "cblas.h"
#include "array_alloc.h"

int main( void )
{
  double **a, **A;
  double  *b, *B, *C;

  int *ipiv;
  int n, nrhs;
  int info;
  int i, j;

  printf( "How big a matrix?\n" );
  fscanf( stdin, "%i", &n );

  /* Allocate the matrix and set it to random values but
     with a big value on the diagonal. This makes sure we don't
     accidentally get a singular matrix */
  a = alloc_2d_double( n, n );
  A= alloc_2d_double( n, n );

  for( i = 0; i < n; i++ ){
    for( j = 0; j < n; j++ ){
      a[ i ][ j ] = ( ( double ) rand() ) / RAND_MAX;
    }
    a[ i ][ i ] = a[ i ][ i ] + n;
  }
  memcpy(A[0],a[0],n*n*sizeof(double)+1);


  /* Allocate and initalise b */
  b = alloc_1d_double( n );
  B = alloc_1d_double( n );
  C = alloc_1d_double( n );

  for( i = 0; i < n; i++ ){
    b[ i ] = 1;
  }

  cblas_dcopy(n,b,1,B,1);
  /* the pivot array */
  ipiv = alloc_1d_int( n );

  /* Note we MUST pass pointers, so have to use a temporary var */
  nrhs = 1;

  /* Call the Fortran. We need one underscore on our system*/
  dgesv_(  &n, &nrhs, a[ 0 ], &n, ipiv, b, &n, &info );

  /* Tell the world the results */
  printf( "info = %i\n", info );
  for( i = 0; i < n; i++ ){
    printf( "%4i ", i );
    printf( "%12.8f", b[ i ] );
    printf( "\n" );
  }

  /* Want to check my lapack result with blas */

cblas_dgemv(CblasRowMajor,CblasTrans,n,n,1.0,A[0],1,B,1,0.0,C,1);

return 0;
}

Answer 1

领先维度(LDA)至少需要与RowMajor矩阵的列数(n)一样大。你的LDA值是1。

另外，我对您的矩阵类型有些怀疑；如果不了解alloc_2d_double是如何实现的，就无法确定您是否正确地布局了矩阵。一般来说，将指针到指针样式的“矩阵”与BLAS样式的矩阵(具有行或列步长的连续数组)混合在一起是一种代码气味。(然而，正确的操作是可能的，而且您很可能正在正确地处理它；只是不可能从您发布的代码中判断是否是这种情况)。