Re: [ublas] Matrix 'View' class

Subject: Re: [ublas] Matrix 'View' class
From: Andrey Asadchev (asadchev_at_[hidden])
Date: 2010-07-27 12:24:18

On Tue, Jul 27, 2010 at 11:11 AM, Andy Somogyi <somogyie_at_[hidden]>wrote:

> Hello All
>
> I frequently work where an external routine gives me a block of memory that
> I need to access as a 2 dimensional matrix (row-major).
>
> I've written a 'matrix-view' class attached below. I plan on just reading
> and writing to the memory block (that I don't own) using this view class.
> I've tested it with a variety of test cases (reading, writing, assigning to
> and from other matrices), and have not come into any problems. Would you
> guys care to take a look at this class, and let me know if there are any
> potential problems with this design, and I think a class like this would be
> of great utility to boost, any possibilities of submitting it?
>
> thanks.
>
>
>
> namespace boost { namespace numeric { namespace ublas {
>
> template<class T, class L=row_major >
> /**
> * a temporary 'view' of an existing 2-dimensional block of
> * memory.
> */
> class matrix_view : public matrix<T, L, shallow_array_adaptor<T> > {
> typedef typename  shallow_array_adaptor<T>::size_type size_type;
> typedef matrix<T, L, shallow_array_adaptor<T> >  base_type;
> public:
> /**
>  * create a matrix_view that is a view of an existing block of data.
>  * the matrix_view does NOT own the given pointer, user is responsible
>  * for making sure that this class is not used after the p_data
>  * block has been freed.
>  */
> matrix_view (size_type size1, size_type size2, T* p_data) :
>  base_type(size1, size2, shallow_array_adaptor<T>(size1*size2, p_data))
> {};
>
> private:
> /**
>  * hide ctors of base class, can only have a matrix_view that is attached
> to
>  * an existing block of data.
>  */
> matrix_view() {};
> matrix_view(size_type size1, size_type size2) {};
> };
> }}};
>
> // example of use, assign identity matrix to given data block,
> // assuming rows == columns.
> void myFunc(int rows, int columns, double* pData) {
> matrix_view<double> mv(rows,colums,pData);
> identity_matrix<double> i(rows);
> mv = i; // the data block referenced by pData is now initialized to the
> identity matrix.
> }
>
>
>
>
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> Sent to: asadchev_at_[hidden]
>

looks very similar to:
http://www.guwi17.de/ublas/examples/storage_adaptors.hpp