eigenmatrix_right returns inconsistent results for eigenvectors

[rbeezer]

Doctests introduced in #4756 return the negative of certain eigenvectors on certain hardware.

See initital discussion at

http://groups.google.com/group/sage-release/browse_thread/thread/9136569bd1c67f6

CC: @jhpalmieri @aghitza

Component: linear algebra

Author: Rob Beezer

Reviewer: William Stein, John Palmieri

Merged: sage-4.4.alpha1

Issue created by migration from https://trac.sagemath.org/ticket/8710

[rbeezer]

Attachment: trac_8710-eigenvector-doctest.patch.gz

[rbeezer]

comment:2

This patch massages the doctests that were causing failures for 4.4.alpha0 on the Skynet machine, sextus. Its not pretty, but I hope the results are now hardware-neutral.

Alex - you reviewed the original ticket (#4756), so maybe this would be an easy review for you?

John - I don't know if it is easy for you to test this on sextus in advance of merging it? Sounds like it will be a while before I have that kind of access.

Rob

[rbeezer]

Author: Rob Beezer

[williamstein]

comment:3

1. John will have to test, since he has the build on sextus.

2. The doctests actually look much nicer normalized to have first entry 1!

(I would give this a positive review if this works.)

[rbeezer]

comment:4

Replying to @williamstein:

2. The doctests actually look much nicer normalized to have first entry 1!

The output looks nicer because this matrix is out of my textbook and was designed to have nice-looking answers. I don't like the hard-to-decipher code that gets you there, but that's the way it goes. Thanks for having a look and for the advice on getting this squared away.

Rob

[jhpalmieri]

Reviewer: William Stein, John Palmieri

[jhpalmieri]

comment:5

Tests pass on sextus. I'll test it on a few more machines, and if it works, I'll give it a positive review and merge it into 4.4.alpha1.

[rbeezer]

comment:6

Hi John,

Did this eventually past muster on skynet, or does it need more testing?

I still haven't done the SciPy tests I'd like to do skynet yet, but hope to get to that soon.

Rob

[jhpalmieri]

Merged: sage-4.4.alpha1

[jhpalmieri]

comment:7

Sorry, Rob. This was actually merged in 4.4.alpha1 but I forgot to mark it as closed. (So it didn't get recorded in the release notes, either.)