- GiNaC-list - ginac.de

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

3 2

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. \\

1 0

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

1 0

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.

2 1

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

2 1

patch: put ginac.pc into libginac-dev
by varg＠thsun1.jinr.ru 06 Oct '04

06 Oct '04

Hello! This small patch slightly changes packaging rules to get ginac.pc included into libginac-dev. Best regards, Alexei.

2 1

var list
by Ralf Stephan 05 Oct '04

05 Oct '04

This must be a faq: Is there a function that returns a lst of all variables in an ex? Or, what's wrong with the following (which leaves symbols empty)? class CollectSymbols_Visitor : public visitor, public symbol::visitor { public: lst symbols; CollectSymbols_Visitor() {} void visit (const symbol& x) { for (lst::const_iterator i = symbols.begin(); i != symbols.end(); i++) if (*i == x) return; symbols.append(x); } }; int main() { symbol x("x"); ex e = x - 2; CollectSymbols_Visitor collector; e.accept (collector); const lst& sym = collector.symbols; cout << sym << endl; }

2 2

simple patch for Li_evalf
by varg＠thsun1.jinr.ru 23 Sep '04

23 Sep '04

Hello! This short program #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main(int argc, char** argv) { ex test = Li(5, exp(I*Pi/3)); cout << test << " = " << test.evalf() << endl; return 0; } gives Li(5,exp((1/3*I)*Pi)) = Li(5,exp((1/3*I)*Pi)) instead of expected Li(5,exp((1/3*I)*Pi)) = 0.48005914589970829926+0.89203268884598503196*I Attached patch seems to solve the problem. Best regards, Alexei.

2 2

Re: [GiNaC-list] quo behaviour
by Ralf Stephan 18 Aug '04

18 Aug '04

> I guess one needs to re-express quo()/rem() in terms of pquo()/prem() to > make that work? Only your question made me aware of prem(). Now, that seems possible but prem() itself appears to have problems: > prem(x*y^3,y*x^3,x); x*y^3 This would (according to the tutorial) satisfy x^(-3)*x*y^3 = y*x^3*q + prem (=x*y^3), so q = pquo() = (x^(-3)-1)*y^2/x^2 which doesn't seem right. There is also the problem of quo() returning a fail (decompose_rational() needs it) which surprised my computations, giving an error, something with commutativity, and I needed some time to see that I was working with a fail that I got from quo(). Thanks, ralf

1 0

quo behaviour
by Ralf Stephan 17 Aug '04

17 Aug '04

Hello, sorry for bothering you so much, you probably think by now I get paid for this. The tutorial says that parameters to quo() should be univariate polynomials. Is this really necessary, esp. if you also get the main variable as parameter? Even if I accept the univariateness for parameters[*], the behaviour of the function towards multivariate input is inconsistent, as the ginsh session shows: > quo(y,y*x,y); FAIL > quo(y*x,y,y); x Thanks, ralf [*] I do not accept it, as I understand ginac from its interface to be inherently multivariate, except for the diff function, and even that is disputable.

2 2