Re: [eigen] Matrix-Matrix Multiplication gives incorrect results (C++11, sometimes)

[Torbjörn Klatt <opensource@xxxxxxxxxxxxxxxxxx>]

Never mind. Everything's fine. :-)

BTW: My minimal example is not complete and missleading.

Sorry for the noise.


On Thu, 18.09.2014 10:52:22 Torbjörn Klatt wrote:
> Hi all,
> 
> I'm using dynamic row-major Eigen3 matrices. Within my code I'm generating a
> (n-1)xn matrix (Q_pre) and post-prefix it with a zero-row to get a nxn
> matrix Q. Afterwards I'll need to square it, which gives me QQ. (see
> 'problematic.cpp' in [1])
> 
> However, the resulting matrix QQ has its "last" (bottom-right) entry
> incorrectly computed. (see 'OUT: problematic' in [1])
> 
> I composed a minimal example and compiled it with the same compiler (and
> options) just to discover that everything goes fine.
> 
> Am I missing something? Neither of the tested compilers (GCC 4.8.3, 4..9.1,
> Clang 3.4.2, 3.5.0) on a 64bit openSUSE 13.1 all with Eigen3 3.2.2 has a
> different behaviour. Nor does any of the compilers complain about anything
> when run with `-Wall -Wextra -Wpedantic -g -O0 -std=c++11`.
> 
> Kind regards,
> Torbjörn Klatt
> 
> 
> [1] https://gist.github.com/torbjoernk/70731289e5a8f054bc67

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