Re: [ublas] Layout type

Subject: Re: [ublas] Layout type
From: Gunter Winkler (guwi17_at_[hidden])
Date: 2010-05-04 17:46:23

Hello Andrea,

Andrea Arteaga schrieb:
> How can I know whether a matrix is storing its elements with
> column-major storage or with row-major?
>
> I'm writing a template function which takes as argument a
> boost::numeric::ublas::matrix and performs some computation. I have to
> know whether I must transpose the data or not:
>
> template<class MatrixType>
> void my_func(const MatrixType& matrix)
> {
>     const char * data =
>              reinterpret_cast<const char *>(&matrix(0, 0));
>   
>     /* ... */
> }
>
> I tried with typename MatrixType::layout_type, but this typedef is
> private.

You should use the matrix traits from traits.hpp (see also fwd.hpp):

// dispatcher
template<class MatrixType>
void my_func(const MatrixType& matrix)
{
    my_func(matrix, typename
matrix_traits<MatrixType>::orientation_category());
}

// row major impl
template<class MatrixType>
void my_func(const MatrixType& matrix, const ublas::row_major_tag /*
unused */ )
{
    const char * data =
             reinterpret_cast<const char *>(&matrix(0, 0));
  
    /* ... */
}

mfg
Gunter

__________ Hinweis von ESET NOD32 Antivirus, Signaturdatenbank-Version 5086 (20100504) __________

E-Mail wurde geprüft mit ESET NOD32 Antivirus.

http://www.eset.com