- GiNaC-list - ginac.de

normal() bug-or-feature
by varg＠thsun1.jinr.ru 18 Nov '04

18 Nov '04

Hello! Sometimes running normal() takes *really* long time. I've attached an example, at first glance it looks horrible, but in fact the expression equals zero. The root of the problem seems to be that gcd(e1, e2, &ca, &cb) returns cb in expanded form, as in: #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main(int argc, char** argv) { symbol m1("m1"); symbol m2("m2"); symbol x("x"); ex e1 = pow(x,2)*pow(m1,2) - pow(x,2)*pow(m2,2); ex e2 = pow(pow(x,2)*pow(m1,2)-pow(x,2)*pow(m2,2),100); ex ca, cb, gc; gc = gcd(e1, e2, &ca, &cb, false); cout << c2 << endl; // this won't be just x^198*(m1^2-m2^2)^99. // (m1^2-m2^2)^99 gets expanded. cout << (e1/e2).normal() << endl; // won't print just x^(-198)*(m1^2-m2^2)^(-99), // (m1^2-m2^2)^99 gets expanded return 0; } so normal() in fact expands denominators. Is there any way to fix this bug/feature? Thanks in advance, Alexei.

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Usage question
by Michael Ahern 18 Nov '04

18 Nov '04

Hello All, I have been investigating using GiNac to solve certain equations and was unsure of what is was capable of. Although I saw the lsovle() function for solving systems of linear equations, I was baffled as how to solve a non-linear equation of the form: 0 = deriv(sqrt( (X - x*t)^2 + (Y - y*t)^2 + (Z - z*t - Gt^2)^2 )) Alternatively, if it is not capable of solving such an equation, if you knew of a C/C++ library (short of matlab) that was capable. Thanks, -Mike __________________________________ Do you Yahoo!? Meet the all-new My Yahoo! - Try it today! http://my.yahoo.com

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GiNaC 1.3.0
by Jens Vollinga 14 Nov '04

14 Nov '04

Hi, GiNaC 1.3.0 is out and available. The changes are: - No funny announcements anymore. - The Clifford classes have been generalized to allow working with Clifford algebras generated by arbitrary symmetric tensors or matrices. Also, a lot of new functions for Clifford algebras have been added, including automorphisms and Moebius transformations. [Contribution by V. Kisil] - Added some basic symbolic and numeric integration facilities. [Contribution by C. Dams] - The multiple polylogarithm Li() now evaluates numerically for arbitrary arguments. - New functions G(a,y) and G(a,s,y) added (another notation for multiple polylogarithms). As always, this release can be downloaded from ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC/ Enjoy, Jens

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Re: [GiNaC-list] code: extended gcd
by CRAIGHS＠Nationwide.com 08 Nov '04

08 Nov '04

Okay. Ralf Stephan <ralf(a)ark.in-berlin.de> T To: ginac-list(a)zino.physik.uni-mainz.de Sent by: cc: ginac-list-admin(a)zino.phys ik.uni-mainz.de bcc: Subject: Re: [GiNaC-list] code: extended gcd 11/08/2004 01:49 PM Please respond to ginac-list > The Yap book is now unavailable on the web. No, the ftp server is a bit peculiar. Just try a few times. _______________________________________________ GiNaC-list mailing list GiNaC-list(a)ginac.de http://thep.physik.uni-mainz.de/mailman/listinfo/ginac-list

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Re: [GiNaC-list] code: extended gcd
by CRAIGHS＠Nationwide.com 08 Nov '04

08 Nov '04

The Yap book is now unavailable on the web.

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Inverse of complex matrix
by Jonathan Brandmeyer 05 Nov '04

05 Nov '04

Sometimes, inverting a matrix with complex values does not produce something that, when multiplied by the original, returns the identity. I have attached a program that demonstrates this for one case, which was found by altering checks/check_matricies.cpp to use complex values from sparse_tree(). Is this a known problem? Thanks, -Jonathan Brandmeyer P.S: GiNaC 1.3.0, G++ 3.3.4+ (Debian), CLN 1.1.8, Debian Sid on i386

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An Example of Clifford Algebras Calculations with GiNaC
by Vladimir Kisil 19 Oct '04

19 Oct '04

Hi, I put at arXiv.org 'An Example of Clifford Algebras Calculations with GiNaC'. The link to paper is http://arxiv.org/abs/cs.MS/0410044 and abstract is given below. Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv(a)maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/ ------------------------------------------------------------------------------ \\ Title: An Example of Clifford Algebras Calculations with GiNaC Authors: Vladimir V. Kisil Comments: 20 pages, LaTeX2e, 12 PS graphics in one figure Report-no: LEEDS-MATH-PURE-2004-18 Subj-class: Mathematical Software; Computational Geometry; Graphics; Symbolic Computation \\ This example of Clifford algebras calculations uses GiNaC (http://www.ginac.de/) library, which includes a support for generic Clifford algebra starting from version~1.3.0. Both symbolic and numeric calculation are possible and can be blended with other functions of GiNaC. This calculations was made for the paper math.CV/0410399. Due to course described features of GiNaC should propagate into other software like GNU Octave (http://www.octave.org/) and gTybalt (http://www.fis.unipr.it/~stefanw/gtybalt.html) which uses GiNaC library as a back-end. \\

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GiNaC 1.2.4
by Jens Vollinga 12 Oct '04

12 Oct '04

Hi, GiNaC 1.2.4 is out and available. The changes are: - Added ex::unitcontprim() to compute the unit, content, and primitive parts of a polynomial in one go. - binomial(n, k) evaluates for non-integer arguments n. - Li(2,x) now evaluates for +-I. - Optimized Li(2,x). - Fixed bug in Li(n,x) (if Li(2,x) was calculated with high precision the enlargement of the look-up table caused a segmentation fault). - Fixed another bug in the series expansion of powers, and a bug in power::info(). As always, this release can be downloaded from ftp://ftpthep.physik.uni-mainz.de/pub/GiNaC/ Enjoy, Jens

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bug in series expansion of powers
by varg＠thsun1.jinr.ru 06 Oct '04

06 Oct '04

Hello! This simple program #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main(int argc, char** argv) { symbol x("x"); symbol a("a"); symbol b("b"); ex test = pow(x+a,b); cout << test << " = " << test.series(x,3) << endl; return 0; } gives (x+a)^b = 1+Order(x^3) instead of (x+a)^b = (a^b)+(a^b*b*a^(-1))*x+(1/2*a^b*b^2*a^(-2)-1/2*a^b*b*a^(-2))*x^2+Order(x^3) Attached patch fix this bug.

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GiNaC Application: Ecco
by Kai Ludwig 06 Oct '04

06 Oct '04

Hi Folks, thanks to the GiNaC library, we developped the kinetic facilities of Ecco - A Compiler for (Electro-)Chemistry. GiNaC enables the support of so called 'generic rate laws' that can be used to model any rate expression for the simulation of chemical and/or electrochemical reaction kinetics. Thanks to you all!! Kai -- http://echempp.sourceforge.net Kai Ludwig Institut für Organische Chemie Auf der Morgenstelle 18 72076 Tübingen Tel.: 07071/29-73049 Mail: kai.ludwig(a)uni-tuebingen.de

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