- GiNaC-list - ginac.de

problem about cl_N output format
by Feng Feng 04 Apr '19

04 Apr '19

Hi all, I got a problem with the csrc_cl_N output format, for example, ex expr = pow(1+x(0),-6); expr.print(print_csrc_cl_N(cout)); I got an output as expt( x(0)+1, (--6)) and it seems that "--" should be only one "-". so is it normal or a bug?

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Poles and zeros
by Patrick Schulz 03 Apr '19

03 Apr '19

Hi all, I'm trying to calculate the poles and zeros of a polynomial and I thought some functions to do this, but I can't find anything anymore. Is there any easy option currently to do this? If not, where would I start implementing this? I don't really grok the GiNaC structure. I'm happy to write a pull request (if I get it done). Kind regards, Patrick

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segmentation fault
by Pedro Sosa 28 Mar '19

28 Mar '19

Hello, I have a doubt, can I define a vector of ex?when I run the program throws an error of segmentation fault thanks vector<ex> e; symtab table; table ["r"]=r; parser reader(table); for(int i=0;i<100;i++){ e[i]=reader(formula[i].getFormula()); }

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Matching both variances of varidx
by Matthew Lim 28 Mar '19

28 Mar '19

Hi, I wanted to implement a rule to replace the product of two epsilon tensors with the determinant of a matrix of metric tensors. I found that simplify_indexed works fine but only if at least one of the indices is summed over - calling it on an expression like lorentz_eps(mu,nu,rho,sigma)*lorentz_eps(alpha,beta,gamma,delta) results in no simplification. Implementing this would be no problem if it weren't for the fact that the expression I want to make the replacement in has many instances of lorentz_eps called with different combinations of co- and contra-variant indices - it seems when I call subs, I need to specify the variance of the wildcard in order to make the match so that, for example, ex test = lorentz_eps(mu.toggle_variance(),nu,rho,sigma) test.subs(lorentz_eps(varidx(wildcard(1),4),varidx(wildcard(2),4),varidx(wildcard(3),4),varidx(wildcard(4),4))== #expression#) does not result in any substitution being made. I am not so keen on implementing separate substitutions for all the different combinatoric possibilities of index variances - is there perhaps a simpler way? Thanks for your help, Matthew

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derivative
by Pedro Sosa 24 Mar '19

24 Mar '19

Hello, thanks but I resolve the former problem...besides I have a new onenow the expresion ex that is well casted from the string is not well transformed into a derivative with diff parser reader; e = reader(ramaPrim[i]); cout<<"ex="<<e<<" diff:"<<e.diff(r).subs(r==Pi)<< " i="<<i<<endl; e is well printed and is a function of r but its derivative is cero!What is happening hereThanks

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Runtime error
by Pedro Sosa 24 Mar '19

24 Mar '19

Hello I hope somebody could help me at runtime I have an error:terminate called after throwing an instance of 'GiNaC::parse_error' what(): GiNaC: parse error at line 0, column 0: expected EOF, got: "[" [GiNaC::ex GiNaC::parser::operator()(std::istream&)(parser/parser.cpp:232)] the code is: for(int i=0; i< ramaPrim.size();i++) { parser reader; ex e = reader("ramaPrim[i]"); }

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convert from string to ex
by Pedro Sosa 24 Mar '19

24 Mar '19

Hello I have a problem, I would like convert from string to ex to find the symbolic derivativeis it posible?void chequeaPrim(vector<string> ramaPrim) { for(int i=0; i< ramaPrim.size();i++) { ex = ramaPrim[i]; } } thanks

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Compilation
by Pedro Sosa 13 Mar '19

13 Mar '19

Hello, I install in my Ubuntu Ginac but I don't know how to compile a basic example #include <iostream> #include <ginac/ginac.h> using namespace std; using namespace GiNaC; int main() { symbol x("x"), y("y"); for (int i=0; i<3; ++i) poly += factorial(i+16)*pow(x,i)*pow(y,2-i); cout << poly << endl; return 0; } where I must put this file for ginac.h can be visiblethanks PS: /usr/include/ginac/ginac.h

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cmake patch to find correct python executable
by Till Hofmann 17 Feb '19

17 Feb '19

Hi all, Please consider including the attached patch. With this patch, cmake searches for the correct path of the python2 interpreter and uses that path for calling python, instead of just calling "python". This fixes a bug on Fedora, which no longer has an unversioned python interpreter (i.e., only python2 and python3). It should also avoid using python3 on accident. On a related note, are there any plans to switch to python3? I only had a quick glance and there are some incompatibilities, but most of them seem to be rather straight-forward to fix. Thanks! Till

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Release 1.7.5
by Richard B. Kreckel 17 Feb '19

17 Feb '19

Hi, A new GiNaC version has just been released. The changes are: * Add Markowitz-ordered Gaussian elimination. * Avoid un-normal zeros in matrix::solve(). * Accept exprseq arguments in lsolve(eqns, vars). * Add overload of matrix::rank(solve_algo). * Fix case in G_do_hoelder with real x values which are not cl_R. * Fix an elusive bug in expairseq/add ctor, introduced in 1.7.0. Happy hacking! -richy.

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