[ublas] matrix_row fails with symmetric matrix

Subject: [ublas] matrix_row fails with symmetric matrix
From: Andrea Cassioli (cassioliandre_at_[hidden])
Date: 2010-05-17 17:03:50

Hi guys,
I've just experienced a quite silly bug. I'm currently using a
symmetric matrix to perform some linear algebra calculations, after
that I need to copy one row at the time in a bigger vector. Till now I
have been performing row copying by means of simple hand-made loops.

Now I would like to clean the code, so I 've decided to use matrix_row
adaptors to iterate among all matrix row and use std::copy to perform
the copy operation.

It sounds clean and simple but surprise it does not work! I've write
down a very simple example, which is attached to the message. In fact
the copy is performed accessing the underlying triangular matrix used
to store the symmetric one.

I'm pretty sure I'm doing something wrong, but I would expect the
matrix_row adaptor to behave as a normal vector, that is I would like
to play with it seamlessly.

Am I wrong or it is a bug??

Best Regards,
Andrea Cassioli