August 2016 - GiNaC-devel

[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-568-g6ad2b99
by git＠ginac.de 17 Aug '16

17 Aug '16

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 6ad2b996d58c0b144770e7cf3079386fcd385908 (commit) via c9e4e59df24f6845b4bfe73619749d4b7447b8a4 (commit) from 11c0c610d6f47476b82f3ab118b0be37ed3ef747 (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 6ad2b996d58c0b144770e7cf3079386fcd385908 Author: Richard Kreckel <kreckel(a)ginac.de> Date: Wed Aug 17 22:08:57 2016 +0200 Update ax_cxx_compile_stdcxx.m4. Serial 3 fixes make CXXFLAGS=..., c.f. the macro's upstream revision history. commit c9e4e59df24f6845b4bfe73619749d4b7447b8a4 Author: Vladimir Kisil <kisilv(a)maths.leeds.ac.uk> Date: Wed Aug 17 22:05:13 2016 +0200 Improve performance of clifford_to_lst(). Rewrite get_clifford_comp() so it is less obscure and more efficient. ----------------------------------------------------------------------- Summary of changes: ginac/clifford.cpp | 116 +++++++++++++++++++++----------------------- m4/ax_cxx_compile_stdcxx.m4 | 48 +++++++++--------- 2 files changed, 82 insertions(+), 82 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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Toggling index covariance in simplify_indexed()
by Vladimir V. Kisil 12 Aug '16

12 Aug '16

Dear All, I am confused by the following. The routine simplify_indexed() calls reposition_dummy_indices(), which has the freedom to toggle dummy indices covariance to achieve canonical order. Leaving aside the question "does the position of an index have geometrical/physical significance and can be harmlessly toggled?", I come to the following unpredictability of the GiNaC output in the different runs of the same compiled programme: #include <ginac/ginac.h> #include <fstream> using namespace std; using namespace GiNaC; int main(){ realsymbol x("x"), y("y"); varidx mu(symbol("mu", "\\mu"), 2); ex e = clifford_unit(mu, diag_matrix(lst{-1,-1})); ex V = lst_to_clifford(lst{x,y}, e); cout << V << endl; // -> e~mu*[[x],[y]].mu cout << simplify_indexed(V) << endl; // in different runs can be either // (A) -> e~mu*[[x],[y]].mu (as above) or // (B) -> e.mu*[[x],[y]]~mu cout << canonicalize_clifford(V*V) << endl; // depanding on the above outcomes: // (A) -> (e~mu*e~symbol6)*[[x],[y]].symbol6*[[x],[y]].mu // (B) -> -2*ONE*y^2-[[x],[y]]~symbol6*[[x],[y]]~mu*(e.symbol6*e.mu)-2*x^2*ONE cout << canonicalize_clifford(simplify_indexed(V)*simplify_indexed(V)) << endl; // (A) -> (e~mu*e~symbol10)*[[x],[y]].mu*[[x],[y]].symbol10 // (B) -> -(e~symbol13*e~mu)*[[x],[y]].mu*[[x],[y]].symbol13-2*ONE*y^2-2*x^2*ONE cout << canonicalize_clifford(simplify_indexed(V)*V) << endl; // (A) -> -[[x],[y]]~symbol14*(e.symbol14*e~mu)*[[x],[y]].mu-2*ONE*y^2-2*x^2*ONE // (B) -> -2*ONE*y^2-[[x],[y]]~mu*[[x],[y]]~symbol20*(e.symbol20*e.mu)-2*x^2*ONE cout << canonicalize_clifford(expand_dummy_sum(simplify_indexed(V)*V)) << endl; // (A) -> -y^2*ONE-x^2*ONE // (B) -> y^2*(e.1*e~1)+x^2*(e.0*e~0)+x*y*(e.0*e~1)-x*y*(e~0*e.1) return 0; } Any advice on usability/necessity of this behaviour? 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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[SCM] GiNaC -- a C++ library for symbolic computations branch, master, updated. release_1-4-0-566-g11c0c61
by git＠ginac.de 12 Aug '16

12 Aug '16

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 11c0c610d6f47476b82f3ab118b0be37ed3ef747 (commit) via 96fc556787518794919137fc6d0e98e002c32ff5 (commit) from 33a92d56aeaadfe8dad246ae17b091e14b220e82 (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 11c0c610d6f47476b82f3ab118b0be37ed3ef747 Author: Stefan Weinzierl <weinzierl(a)uni-mainz.de> Date: Thu Aug 11 23:55:59 2016 +0200 Fix convergence of Li_projection at ±I. For arguments near ±I, direct summation does not practically converge. Use the Bernoulli transformation instead. Thanks to Peter Banks for reporting this: <http://www.cebix.net/pipermail/ginac-list/2016-August/002085.html> commit 96fc556787518794919137fc6d0e98e002c32ff5 Author: Vladimir Kisil <kisilv(a)maths.leeds.ac.uk> Date: Thu Aug 11 20:47:08 2016 +0200 Add proper functions to make clifford_bar() and clifford_star(). Previously operations clifford_bar() and clifford_star() called conjugate() method. This results in reversion of all non-commutative entries (not only Clifford units) and produced complex conjugation of all non-real items. The new routine operates on Clifford units only. ----------------------------------------------------------------------- Summary of changes: check/exam_clifford.cpp | 41 ++++++++++++++++++++++++++++++++++++++++- doc/tutorial/ginac.texi | 7 +++---- ginac/clifford.cpp | 41 +++++++++++++++++++++++++++++++++++++++++ ginac/clifford.h | 10 +++++++--- ginac/inifcns_nstdsums.cpp | 7 ++++--- 5 files changed, 95 insertions(+), 11 deletions(-) hooks/post-receive -- GiNaC -- a C++ library for symbolic computations

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Improvement for get_clifford_comp()
by Vladimir V. Kisil 11 Aug '16

11 Aug '16

Dear All, The previous version of get_clifford_comp() was written in obscure and inefficient way. I am attaching a new version which still passes all tests in exam_clifford.cpp ;-) 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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Bug fix multiple polylogarithms
by Stefan Weinzierl 11 Aug '16

11 Aug '16

Dear all, the attached patch fixes the problem reported in <http://www.cebix.net/pipermail/ginac-list/2016-August/002085.html> This concerns the function Li_projection, which no longer uses for arguments x near +/- I the direct summation (which practically does not converge), but uses the Bernoulli transformation instead. Best regards, Stefan

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[PATCH] Proper functions to make clifford_bar() and clifford_star()
by Vladimir V. Kisil 09 Aug '16

09 Aug '16

Dear All, Previously operations clifford_bar() and clifford_star() called conjugate() method. This results in reversion of all non-commutative entries (not only Clifford units) and produced complex conjugation of all non-real items. The new routine operates on Clifford units only. The test and documentations are updated accordingly. 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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