#14403: Symbolic charpoly broken
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Reporter: nbruin | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-5.11
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Dependencies:
Stopgaps: |
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Comment (by ppurka):
Replying to [comment:7 nbruin]:
> Please look at the sage-devel thread referenced. Part of the problem
here is the use of the routine "polynomial", which is dodgy for examples
like:
> {{{matrix([[y^(1/2),0,0,0],[0,1,0,0],[0,0,1,0],[0,0,0,1]]) }}}
> You know that the expression returned by maxima's charpol is already
presented as a polynomial in the (better unique!) variable used to do the
expansion. The code proposed in the ticket is both more robust and faster.
Ok. I see. The main concern is this it seems (quoted from the sage-devel
ML):
''
(You really don't want to let 'crazy_varname' leak out of charpoly,
otherwise you'll have trouble if someone decides to make a matrix of
characteristic polynomials and determine the charpoly of that. You
also don't want to generate a fresh variable every time, since the
management of variables in maxima/our interface would create a memory
leak)
''
@gagern: can you try converting the code in the ticket description into a
patch (along with a doctest)?
--
Ticket URL: <http://trac.sagemath.org/ticket/14403#comment:8>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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