Re: [ublas] example usage of coordinate_matrix fails on Ubuntu 11.04 (amd_64)

Subject: Re: [ublas] example usage of coordinate_matrix fails on Ubuntu 11.04 (amd_64)
From: David Bellot (david.bellot_at_[hidden])
Date: 2011-12-11 14:08:43

thanks Thomas, I'll have a look at that quickly and push that into 1.49

On Sun, Dec 11, 2011 at 11:47, Thomas Klimpel
<Thomas.Klimpel_at_[hidden]>wrote:

> David Bellot wrote:
> > if it's ublas related, then no, because 1.48 is not different than 1.47
> (w.r.t ublas).
> > I don't really have time these days to work on a solution due to my
> current job,
> > but if someone has a patch I'll have time enough to push it for 1.49.
>
> Well, the failing line is in
> boost/numeric/ublas/matrix_sparse.hpp:4403:
>                std::inplace_merge (ita.begin (), iunsorted, ita.end ());
>
> The attached patch modifies "std::inplace_merge" appropriately...
>
> The issues boils down to the fact that for "Forward Iterators", the return
> value of "*a" must be convertible to "T&" (see for example <
> http://stdcxx.apache.org/doc/stdlibref/iterators.html>). But a temporary
> value cannot bind against a non-const reference, so these requirements can
> only be satisfied if the return value of "*a" actually has the type "T&"
> (please correct me if I'm wrong). But this makes it impossible to use
> proxy_objects with iterators, and hence makes many actual usages of
> iterators (like this one here) impossible, or at least not standard conform
> (again, please correct me if I'm wrong). The reactions to related issues in
> Boost.Multi_Array/Boost.Iterator (see <
> http://lists.boost.org/Archives/boost/2011/11/187501.php>) don't motivate
> me to invest much of my time into this issue.
>
> The issue here could also be solved by replacing the call to
> std::inplace_merge with a "hand-rolled" implementation of "inplace_merge".
> Note however that the implementation should be based neither on "Dinkum STL
> library by P.J. Plauger" (=stl used by MSVC), nor on "libstdc++ from gnu"
> (=stl used by gcc/g++), because their licenses are not compatible with the
> boost license. Some of the stl implementations referred to at <
> http://en.wikipedia.org/wiki/Standard_Template_Library#Implementations>
> (probably) have a usable license, but I would have to ask somebody like Ion
> Gaztañaga or Vicente Botet to find out details (like where/whether I would
> have to put acknowledgments and license text/references). One could also
> try to rewrite "inplace_merge" from scratch, but my own motivation for
> doing that is pretty low.
>
> Regards,
> Thomas
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