June 2009 - GiNaC-list

GiNaC and Scilab
by Jorge Cardona 10 Jul '09

10 Jul '09

Hi, My name is Jorge Eduardo Cardona, i'm working rigth now on GSoC with Scilab, my project consist in add a symbolic module to it. In order to do that i had choose GiNaC library for it, and your ToDo list has two topics in which i want to work: Limits and symbolic integration. Well, about integrals i check the source and found a little piece of code that expands integrals (integrals.cpp) and resolve integrals on pow types, and with it solve polynomial integrals. I was thinking in start there to add more methods, but i want to know if there is some work already done. One way could be to add an argument to REGISTER_FUNCTION and pass an integral_func(...) as the extra argument, and we have then integrals for all the functions registered, and we can then start to use more heuristic methods on integrals.cpp, well thats just an initial idea, i want to know all the previous ideas on it to start to work. With limits, i don't even look at the code for it, but this night i will check it. Well, please let me know what do you think about it, you can see a wiki with information in: http://wiki.scilab.org/Gsoc2009Symbolic, and the code on: http://gitweb.scilab.org/?p=symbolic;a=summary. I'm reading some papers on ACM Digital Library about symbolic integration, specially Symbolic integration: the stormy decade, and the one that is linked at the TODO list(that link is actually broken: http://www-sop.inria.fr/cafe/Manuel.Bronstein/publications/issac98.pdf) Well, i really want to add these features to GiNaC and then use it on scilab, please let me know everything about it, what do you expect of it? what basic guidelines on code writing, basic ideas, anything. Bye. -- Jorge Eduardo Cardona jorgeecardona(a)gmail.com jorgeecardona.blogspot.com ------------------------------------------------ Linux registered user #391186 Registered machine #291871 ------------------------------------------------

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Non commutative symbols ?
by ahabrard 30 Jun '09

30 Jun '09

Hello, We are new to the Ginac community and we want to manipulate non commutative symbols. We didn't find how to declare non commutative symbols in the tutorial and we found this on the web: const unsigned tinfo=2; symbol x("x", return_types::noncommutative,&tinfo) But we don't know if this declaration is correct ? We will appreciate any documentation on using non commutative symbols. We tried the following code: const unsigned tinfo=2; symbol x("x", return_types::noncommutative,&tinfo); symbol y("y",return_types::noncommutative,&tinfo); cout << x*y+y*x+x*y << endl; cout << x/x << endl; cout << x*pow(x,-1) << endl; The first expression works fine, however the last two expressions are not simplified to the neutral element. Is there anyone who knows the reason ? Another problem with matrix of non commutative symbols, consider the following code: matrix m(2,2); m = x, y, y, x; cout << m.inverse() << endl; Ginac stops with the following message: "Terminate called after throwing an instance of 'std::logic_error' what(): add::eval(): sum of non-commutative objects has non-zero numeric term Abort trap" Anyone knows the reason ? Thanks in advance for your help. Best regards, Amaury -- View this message in context: http://www.nabble.com/Non-commutative-symbols---tp24257628p24257628.html Sent from the Ginac - General mailing list archive at Nabble.com.

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parse own function
by Jan.M 14 Jun '09

14 Jun '09

hello, i'm new to ginac and got some problems with parsing own functions: #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; DECLARE_FUNCTION_3P(myfct) REGISTER_FUNCTION(myfct,dummy()) int main(int argc, char **argv){ symbol x("x"),y("y"); lst all; all = x,y; string str = "myfct(x,y,2)"; ex e(str, all); cout << e << endl; return 0; } ---> terminate called after throwing an instance of 'GiNaC::parse_error' what(): GiNaC: parse error at line 0, column 0: no function "myfct" with 3 arguments [GiNaC::ex GiNaC::parser::parse_identifier_expr()(parser/parser.cpp:66)] have i forgot something? thanks in advance. jan -- View this message in context: http://www.nabble.com/parse-own-function-tp24001248p24001248.html Sent from the Ginac - General mailing list archive at Nabble.com.

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Re: [GiNaC-list] GiNaC::marix::solve(..)
by Lisa Maletzki 04 Jun '09

04 Jun '09

> Message: 1 > Date: Tue, 02 Jun 2009 18:37:08 +0200 > From: Lisa Maletzki <l.maletzki(a)tu-bs.de> > Subject: [GiNaC-list] GiNaC::marix::solve(..) problem > To: ginac-list(a)ginac.de > Message-ID: <20090602183708.y2zyinropw4o840k(a)webmail.tu-bs.de> > Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; > format="flowed" > > Hey, > > I have a smallish problem with the method mentioned above > (matrix::solve(..)). I have two nxn numeric matrices A and b (from the > equation Ax=b) and of course want the matrix x in the end but I keep > on getting the error that the first argument must be a matrix of > symbols. Now my question how can I do that? I tried it with ex > symbolic_matrix(..) but I couldn't get it to work since it is of the > type ex and not matrix. > > Kind regards, > > Lisa > > > > ------------------------------ > > Message: 2 > Date: Tue, 02 Jun 2009 19:35:08 +0200 > From: Jens Vollinga <jensv(a)nikhef.nl> > Subject: Re: [GiNaC-list] GiNaC::marix::solve(..) problem > To: GiNaC discussion list <ginac-list(a)ginac.de> > Message-ID: <4A2562CC.2020405(a)nikhef.nl> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi, > > Lisa Maletzki schrieb: >> I have a smallish problem with the method mentioned above >> (matrix::solve(..)). I have two nxn numeric matrices A and b (from the >> equation Ax=b) and of course want the matrix x in the end but I keep on >> getting the error that the first argument must be a matrix of symbols. >> Now my question how can I do that? I tried it with ex >> symbolic_matrix(..) but I couldn't get it to work since it is of the >> type ex and not matrix. > > take the following example as a guide: > > matrix A(2,2); > A = 1, 2, 3, 4; > symbol x1("x1"), x2("x2"); > matrix x(2,1); > x = x1, x2; > matrix b(2,1); > b = 5, 6; > cout << A.solve(x, b) << endl; > > As the manual warns, you will get an exception thrown if the system is > overdetermined. A more robust version is shown in the following example > using no matrices: > > symbol x1("x1"), x2("x2"); > lst equations; > equations.append(1*x1 + 2*x2 == 5); > equations.append(3*x1 + 4*x2 == 6); > cout << lsolve(equations, lst(x1,x2)) << endl; > > Regards, > Jens > Thank you Jens. But the problem I have is, that I do not know how big my matrix will be. In the smallest case it is a 18x18 matrix, so getting all those symbols would be rather complicated, or am I just thinking that? Kind regards, Lisa

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GiNaC::marix::solve(..) problem
by Lisa Maletzki 02 Jun '09

02 Jun '09

Hey, I have a smallish problem with the method mentioned above (matrix::solve(..)). I have two nxn numeric matrices A and b (from the equation Ax=b) and of course want the matrix x in the end but I keep on getting the error that the first argument must be a matrix of symbols. Now my question how can I do that? I tried it with ex symbolic_matrix(..) but I couldn't get it to work since it is of the type ex and not matrix. Kind regards, Lisa

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