[eigen] SVD Bug

[Hauke Heibel <hauke.heibel@xxxxxxxxxxxxxx>]

Hi,

the user chef_seppel has found a bug in the SVD. Here is the post
http://forum.kde.org/viewtopic.php?f=74&t=90425. I can confirm it is a
bug.

In principle, the attached patch should fix it. I also changed the
unit test and according to our docs
(http://eigen.tuxfamily.org/dox/classEigen_1_1SVD.html) I would expect
any m-by-n matrix A to be working (when m>n). But the unit test fails
even for the most simple example where A is 3-by-2, x is 2-by-1 and b
is 3-by-1. The failure is caused by the solve part.

I tried to look into it but failed. I can only say that already the
matrix U is strange since its last row is zero and this should not be
the case.

I know that Benoit is still working on rewriting the SVD but at least
the bad memory access should be fixed.

Cheers,
Hauke

Attachment: svd_fix.patch
Description: Binary data