Re: [ublas] Reduced performance with new ublas version on XLC++

From: Andreas Dolfen (a.dolfen_at_[hidden])
Date: 2006-04-20 05:59:55

> What type of matrices do you use? Did you try the current CVS-Head of ublas, 
> too? Do you use the const version of operator(i,j) wherever possible?
Ohh, I should have said that it is an ordinary dense matrix
matrix<double, column_major> mat;

I think I use the const version of the operator(i,j) because I call it
by a const reference.

const matrix<T_t> &hupt = hup->t;

No, I did not try the CVS-HEAD version yet but I will try it later!

> The operator[i] of a matrix returns an instance of the matrix_row proxy. The 
> operator(i,j) directly addresses single elements. You can have the old 
> behavior if you define
Yeah, that is why I thought that the operator(i,j) should be faster.
> #define BOOST_UBLAS_ENABLE_PROXY_SHORTCUTS 1
I'll try my old code with the new ublas and
BOOST_UBLAS_ENABLE_PROXY_SHORTCUTS.

> We are not aware of a general performance decrease. Could you provide a simple 
> test case that shows this effect?
Ok, I will try to provide a simple test.

Many thanks

Andreas