Blas DGEMV input error -

i'm having trouble figuring out why piece of blas call throwing n error. problem call last blas call. code compiles without issue , runs fine until call fails following message.

** acml error: on entry dgemv parameter number 6 had illegal value

as far can tell input types correct , array has appreciate insight problem. thanks

#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 matrix?\n" );   fscanf( stdin, "%i", &n );    /* allocate matrix , set random values      big value on diagonal. makes sure don't      accidentally singular matrix */   = alloc_2d_double( n, n );   a= alloc_2d_double( n, n );    for( = 0; < n; i++ ){     for( j = 0; j < n; j++ ){       a[ ][ j ] = ( ( double ) rand() ) / rand_max;     }     a[ ][ ] = a[ ][ ] + n;   }   memcpy(a[0],a[0],n*n*sizeof(double)+1);     /* allocate , initalise b */   b = alloc_1d_double( n );   b = alloc_1d_double( n );   c = alloc_1d_double( n );    for( = 0; < n; i++ ){     b[ ] = 1;   }    cblas_dcopy(n,b,1,b,1);   /* pivot array */   ipiv = alloc_1d_int( n );    /* note must pass pointers, have use temporary var */   nrhs = 1;    /* call fortran. need 1 underscore on our system*/   dgesv_(  &n, &nrhs, a[ 0 ], &n, ipiv, b, &n, &info );    /* tell world results */   printf( "info = %i\n", info );   for( = 0; < n; i++ ){     printf( "%4i ", );     printf( "%12.8f", b[ ] );     printf( "\n" );   }    /* want check lapack result blas */  cblas_dgemv(cblasrowmajor,cblastrans,n,n,1.0,a[0],1,b,1,0.0,c,1);  return 0; } 

the leading dimension (lda) needs @ least large number of columns (n) rowmajor matrix. you’re passing lda of 1.

separately, i’m suspicious of matrix types; without seeing how alloc_2d_double implemented there’s no way sure if you’re laying out matrix correctly or not. speaking, intermixing pointer-to-pointer-style “matrices” blas-style matrices (contiguous arrays row or column stride) of code smell. (however, possible correctly, , may handling properly; it’s not possible tell if case code posted).