March 2015 - GiNaC-devel

04 Jun '15

Hi, is there any reason not to define the derivative of the built-in abs() function as either abs(x)/x or csgn(x) ? Currently it has not derivative defined at all. Regards, Jan

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compile_ex with HAVE_LIBDL with cmake build system
by Martin Vala 14 Apr '15

14 Apr '15

Dear ginac dev, i would like to use function compile_ex and it is not possible to set using cmake build system. I added some cmake configuration and all changes are in tarball http://alice.saske.sk/mvala/ginac/ginac-1.6.3.tar.bz2 Can you add this to 1.6.4? It would help me a lot. Thanks Ciao Martin

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Revised patch: Power transformation for real base and positive exponent
by Vladimir V. Kisil 22 Mar '15

22 Mar '15

Dear All, I am attaching the revised patch to power::expand(), which make the transformation: (x*p)^c --> x^c * p^c, if p>0 and c is real This seems to be helpful in many cases. A corresponding check is added as well. Best wishes, Vladimir -- Vladimir V. Kisil http://www.maths.leeds.ac.uk/~kisilv/ Book: Geometry of Mobius Transformations http://goo.gl/EaG2Vu Software: Geometry of cycles http://moebinv.sourceforge.net/

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Normal on nested functions
by Ladislav Zejda 14 Mar '15

14 Mar '15

Dear developers, first let me thank you for the excellent job you are doing. Recently I have found out a problem during the computation of the numerator and the denominator of expressions involving nested functions. A simple example is enclosed in the file test_normal.cc . Output of the program linked against the current git repository or the version 1.6.3 is in the file test_normal.log . Though the denominator of both terms is the same, the program returns the square of it. I looked into the source code. Seem like functions replace_with_symbol(const ex & e, exmap & repl, exmap & rev_lookup) and replace_with_symbol(const ex & e, exmap & repl) defined in the file normal.cpp search repl for an original expression but insert into repl alredy substitued expression. Then the repeated search does not work and a new symbol is introduced. I tried to fix it with the enclosed patch normal.cpp.patch. Is it acceptable as a solution of the problem? Best regards, Ladislav Zejda

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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-444-g0b985d5
by git＠ginac.de 14 Mar '15

14 Mar '15

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 0b985d5336debdd396f0fbeca8df850af5f569f4 (commit) from 1994570795185f89cc848843cc53664740d20fa0 (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 0b985d5336debdd396f0fbeca8df850af5f569f4 Author: Ladislav Zejda <lzejda(a)gmail.com> Date: Sat Mar 14 11:12:11 2015 +0100 Improve normalization with nested functions. normal() fails to fully normalize expressions where nested functions occur multiple times because replace_with_symbol() searches repl for an original expression but inserts into repl the substitued expression. Then the repeated search does not work and a new symbol is introduced. This patch fixes that by searching for the expression with the repl substituted instead of for the original expression. ----------------------------------------------------------------------- Summary of changes: check/exam_normalization.cpp | 7 ++++++- ginac/normal.cpp | 16 ++++++++++------ 2 files changed, 16 insertions(+), 7 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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