Re: [eigen] Matrix multiplication seems to be exceptionally slow in one specific case

[Marc Glisse <marc.glisse@xxxxxxxx>]

On Tue, 17 Jun 2014, Christoph Hertzberg wrote:

> > >  auto AB = A*B;          // shall this evaluate into a temporary?
> >
> > Write auto&& (or auto const&) if you don't want value semantics.
>
> Wouldn't that lose C++11 compatibility?

I believe this is already fine in C++11. The main drawback of using 
references there is:
auto && x = + f(y);
where f(y) returns a prvalue (a temporary) and operator+ returns a 
reference to its argument (tempting despite the danger). In this case x 
becomes a dangling reference, while "auto x" would have safely made a 
copy before the temporary got out of scope.

--
Marc Glisse