Re: [Help-gsl] Wrong result in vector from gsl_vector_alloc_col_from_matrix

[Stephan Petzchen]

Same problem with the function: gsl_matrix_column which return a vector
view. When this intended then the selected vector size as matrix.size1 (no.
of rows) is quite confusing.

On Tue, Nov 13, 2012 at 6:41 PM, Stephan Petzchen <
address@hidden> wrote:

> Hi,
>
> I am working on the 1.15 version of GSL and get a wrong result in vector v
> from gsl_vector_alloc_col_from_matrix.  (matrix/gsl_vector_double.h,
> matrix/getset_source.c)
>
> My understanding is that it should return the matrix column data for a
> specified column. So, with gsl_vector_alloc_row_from_matrix, here the
> specified row will be returned.
>
> Example:
>
> Matrix:
> 1 1 1 1 1 1 1
> 2 2 2 2 2 2 2
> 3 3 3 3 3 3 3
> 4 4 4 4 4 4 4
>
> Expected result for column offset 4 with vector size 4 (specified by no.
> of matrix rows): 1 2 3 4
> x x x x 1 x x
> x x x x 2 x x
> x x x x 3 x x
> x x x x 4 x x
>
> Actual result:
> x x x x 1 1 1
> 2 x x x x x x
> x x x x x x x
> x x x x x x x
>
>
> I am not sure but it should work similar to int *gsl_matrix_get_col* 
> *(gsl_vector
> * v, const gsl_matrix * m, size_t j), at least the result should be the
> same. At least this is my understanding actually.*
> *
> *
> *Maybe someone can help me when I am wrong in my understanding and the
> actual behavior is the way it should work and data is only given from the
> matrix column offset on with matrix no. of rows as vector size. But this
> makes for me less sense why this vector size is than chosen.*
> *
> *
> *Thanks for you help.*
> *
> *
> *STephan*
>
>
>


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