#12514: default behavior of matrix([...]).eigenvectors_right() should be sane
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Reporter: ppurka | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-5.0
Component: linear algebra | Keywords: matrix eigenvectors
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by rbeezer):
Replying to [comment:4 ppurka]:
>
> Then how about the other option? Use RDF only if the code when run over
RR returns with `NotImplementedError`? This would leave the `ZZ` or `QQ`
case alone.
Converting from RR to RDF could mean a massive loss of precision (it seems
possible, I checked). So there are two situations:
(1) A matrix is entered with decimals and no base ring. User gets RR
matrix. Eigenvalues are poorly implemented, eigenvectors quit.
(2) A matrix has RR entries to a high precision and the user likes it this
way. Eigenvalues gives a warning (good), eigenvectors fails (better than
a poor implementaion IMHO).
How about the following to satisfy both situations? Implement all the
eigenstuff for RR/CC matrices by doing a conversion immediately, and then
using output of the RDF/CDF routines. Maybe with a one-time warning like
we do now for eigenvalues over RR/CC and good documentation. That way, if
anybody ever gets excited about implementing numerical routines properly
for RR/CC, the conversion will get replaced.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12514#comment:5>
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