Re: [ublas] matrix expressions (was find2 required by Matrix)

From: Nico Galoppo (nico_at_[hidden])
Date: 2005-11-26 16:57:27

Michael Stevens wrote:
> E will NOT in general  be a concrete Matrix class. In fact it will only be a 
> concrete matrix class in the case where 'determinant' is called with a 
> concrete matrix argument. This is because a Matrix class must be dervived 
> thus
> 	class matrix : public matrix_container<matrix>
> and
> 	template <class C>
> 	class matrix_container : public matrix_expression<C>
> 

I was wondering what the performance implications of this are, eg. I have a 
templated function:

template <typename Mat> func(Mat& M)

versus

template <typename C> func(matrix_container<C>& M)

In the second example, to perform operations on the data, it seems that I need 
to apply the operator() on M every time, like

size_type n = M().size1();
or
atlas::gemm(M(), ...);

What is the performance hit of applying operator() in this case? I was looking 
at the second approach such that the compiler can distinguish between

template <typename C> func(matrix_container<C>& M)
template <typename C> func(vector_container<C>& V)

I couldn't do that with the first appraoch...

Thanks,

--nico
-- 
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