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August 2020

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-669-gf1a824bb
by Richard B. Kreckel 03 Aug '20

03 Aug '20

This is an automated email from the git hooks/post-receive script. It was generated because a ref change was pushed to the repository containing the project "GiNaC -- a C++ library for symbolic computations". The branch, master has been updated via f1a824bb5b7535c26c75ef03615179680c0f9753 (commit) via cdddbc6dcdabef73aeb20bb9b81e08dba92a235c (commit) from c2ef6cb074a85957bd684337552fe9d84451d307 (commit) Those revisions listed above that are new to this repository have not appeared on any other notification email; so we list those revisions in full, below. - Log ----------------------------------------------------------------- commit f1a824bb5b7535c26c75ef03615179680c0f9753 Author: Richard Kreckel <kreckel(a)ginac.de> Date: Mon Aug 3 18:20:27 2020 +0200 Make workarounds for sqrfree_yun() obsolete. Since Yun's algorithm is based on polynomial GCD, it only finds factors up to a unit. Callers shouldn't have to work around this, so sqrfree_yun() now does a final polynomial long division to compute the lost factor and fixes the result before returning. commit cdddbc6dcdabef73aeb20bb9b81e08dba92a235c Author: Richard Kreckel <kreckel(a)ginac.de> Date: Mon Aug 3 18:09:30 2020 +0200 [BUGFIX] Fix factor_univariate(poly, x) for constant poly. The modular factorization fails to find a prime in this case, leading to an infinite loop. At least one caller (factor_sqrfree) happens to produce such constant polys in some cases. ----------------------------------------------------------------------- Summary of changes: check/exam_factor.cpp | 7 ++---- ginac/factor.cpp | 7 ++++-- ginac/normal.cpp | 70 ++++++++++++++++++++++++++++----------------------- 3 files changed, 46 insertions(+), 38 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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Re: [GiNaC-devel] Sqrfree_parfrac Issue GiNaC
by Vladimir V. Kisil 02 Aug '20

02 Aug '20

Dear Konstantin, Many thanks for reporting the bug with a detailed description. I am attaching a patch to fix it. Best wishes, Vladimir -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Maps https://doi.org/10.1142/p835 Soft: Geometry of cycles http://moebinv.sourceforge.net/ Jupyter notebooks: https://github.com/vvkisil/MoebInv-notebooks ________________________________________ From: GiNaC-list <ginac-list-bounces(a)ginac.de> on behalf of Konstantin Leyde <konstantin.leyde(a)live.com> Sent: 22 July 2020 19:16 To: ginac-list(a)ginac.de Cc: vittorio del duca; Claude Duhr Subject: [GiNaC-list] Sqrfree_parfrac Issue GiNaC Hello, My name is Konstantin Leyde, and I am a master student in physics at the ETH Zurich. For my thesis project, I have been working with the GiNaC library, and I have encountered an issue with the partial fractioning (sqrfree_parfrac) routine: Unless I misunderstood the way the sqrfree_parfrac routine works, it appears that for special cases, the output of the sqrfree_parfrac routine misses a numerical prefactor for one term, and thus returns the wrong answer. Please find attached a pdf, that explains the problem in more detail. In this pdf (as well as separately) we have attached the code that shows the issue. Many thanks in advance, Best wishes, Konstantin

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