- GiNaC-list - ginac.de

variable isolation
by Andrea Monzali 12 Jun '13

12 Jun '13

Good evening everybody, I'm new to ginac, i read the tutorial but i've a question, if I have an equation expression, something like symbol x("x"), y("y"); ex eq = 2*x + 3*x*y - 5*y == 0 is there a method to isolate a single variable, i.e. cout << isolate(eq, x) << endl; // x == 5*y*(2 + 3*y)^(-1) cout << isolate(eq, y) << endl; // y == 2*x*(5 - 3*x)^(-1) thanks for all replies.. -am

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Fwd: find series roots with Ginac
by Jey Nadarasa 22 Apr '13

22 Apr '13

Hello everyone, I would like to know if it is possible to find series roots with Ginac ? That's all for the moment, Advance thanks for your answer, Best Regards, JN

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[(Possible) Bug Report] g++-4.8 (slightly) breaks GiNaC::symbol
by Song Gao 25 Mar '13

25 Mar '13

Hey, I had a weird problem using GiNaC with g++-4.8. It seems that GiNac::symbol will be deleted twice if it's not dynamically declared. In other words, some resources in it is free'd before the automatic destructor is called when the scope finishes. The minimum code to re-produce the issue is: #include <ginac/ginac.h> int main() { GiNaC::symbol x("x"); return 0; } $ g++-4.8 -g -o main main0.cc -lginac -lcln && ./main main(69018) malloc: *** error for object 0x7fff73275570: pointer being freed was not allocated It seems this issue only exists in g++-4.8. g++-4.7 is fine. I briefly looked at symbol.h but did not manage to locate the problem. I was hoping someone here more familiar with the code base could fix it or provide some direction for me. Thanks. -- Song Gao http://song.gao.io/

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GiNaC Multithreading
by Florian 09 Mar '13

09 Mar '13

Hi, I have read the issue of multithreading from 2010 and I wonder whether there has been attempt to make GiNaC thread-safe. I think that it shouldn't be a big deal to make the shared data like the refcounter atomic (e.g. using std::atomic< T >) or to the synchronize it's manipulation (e.g. using std::mutex). Best regards, Florian -- Florian Corzilius RWTH Aachen University Computer Science Department, Informatik 2 D-52056 Aachen, Germany http://www-i2.informatik.rwth-aachen.de/i2/corzilius/ phone: +49 241 80-21244

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cmake msvc build
by Philipp Kraus 25 Feb '13

25 Feb '13

Hello, I love GiNaC and I can build it with MSYS very well. My question is for a feature request is: Can a cmake build added, so that I can build GiNaC native under MSVC? I think this can be a nice solution. Thanks Phil

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subs does not work
by Zhao Li 21 Feb '13

21 Feb '13

Here I am trying to make a substitution. For testing, the function "has" works as shown below. But the "subs" just does not implement the substitution. cout << has(temp, JF1(wild(1), GA(wild(5)), wild(2))*JF1(wild(3), GA(wild(5)), wild(4)) , has_options::algebraic ) << endl; cout << temp.subs( JF1(wild(1),GA(wild(5)),wild(2))*JF1(wild(3),GA(wild(5)),wild(4)) == 2, subs_options::algebraic ) << endl; The functions "JF1" and "GA" are both declared using DECLARE_FUNCTION and commutative. DECLARE_FUNCTION_1P( GA ); REGISTER_FUNCTION( GA, dummy() ); Best regards, Zhao Theory Division Institute of High Energy Physics Chinese Academy of Sciences

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Creating a number of FUNCTION_1P
by Dale Lukas Peterson 20 Feb '13

20 Feb '13

I am trying to declare N GiNaC 1 parameter functions (DECLARE_FUNCTION_1P), each of which represents a different function of the same single parameter (in my case, this parameter represents time). My primary motivation for doing this is to be able to easily create a bunch of symbol-like objects that all depend on time so that I can trust that the chain rule will work properly when differentiating with respect to this single parameter. I think this has come up before, but I haven't seen a way to declare a vector or list of these functions without N explicit statements to DECLARE_FUNCTION_1P. Is there a simple way to do this in GiNaC? Thanks, Luke

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Compilation under macos + question on matrices
by Laurent Bartholdi 16 Feb '13

16 Feb '13

Dear all, I'm new to ginac, and very eager to learn more about it. I installed the latest (1.6.2) version on a recent (mountain lion 12.2.1) system, using the automatic packaging system 'homebrew'. 1. There must be a bug somewhere along the line, because the most naive, simple program from the manual (and all other examples I tried) cause a malloc error: % cat x.C #include <iostream> #include <ginac/ginac.h> int main() { GiNaC::symbol v("v"); std::cout << v << std::endl; return 0; } % g++ x.C -lginac && ./a.out v a.out(31763) malloc: *** error for object 0x7fff7b419570: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug Abort trap: 6 2. Setting matrix entries causes crash: ... GiNaC::matrix m(10,10); m[1][2] = 1; ... causes "libc++abi.dylib: terminate called throwing an exception" 3. I can't find the tensor product of matrices (aka Kronecker product) in the documentation. If M in an axb matrix and N is a cxd matrix, this would be the (ac)x(bd) matrix with entries the products of entries of M and N. While it's easy to implement myself, I'm surprised not to find it in the library. Did I miss something? I'm not sure I know well how this mailing list works, so I'd appreciate a reply directly to my email address. Thanks in advance, Laurent -- Prof. Dr. Laurent Bartholdi \ laurent.bartholdi<at>gmail<dot>com G.-A. Universität zu Göttingen \ Phone: +49 551 39 7826 Bunsenstraße 3-5 \ Secr: +49 551 39 7752 D-37073 Göttingen, Germany \ Fax: +49 551 39 22674

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Re: [GiNaC-list] set_TeX_name() ?
by Dale Lukas Peterson 23 Jan '13

23 Jan '13

> Just as a suggestion: instead of an introduction of a separate > method set_TeX_name(), may be simpler to modify set_name() to have an > optional second argument for the Tex name (similar to the symbol() > method). Here are the three options I can see. First, a default parameter as I think you are suggesting: void set_name(const std::string & n, const std::string & texname = "") { name = n; TeX_name = texname; } Second, overloading set_name: void set_name(const std::string & n) { name = n; } void set_name(const std::string & n, const std::string & texname) { name = n; TeX_name = texname; } Third, the option I originally proposed: void set_TeX_name(const std::string & n) { TeX_name = n; } I prefer my original proposal since it seems the most orthogonal to me. But any of them is really fine with me so that there is a way to change the TeX_name after you've created an instance of symbol. If there is interest in keeping fewer methods, then I guess one of the first two options would be preferable. Thanks, Dale

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Automatic simplification of C# expressions
by Eduardo Cavazos 20 Jan '13

20 Jan '13

Hello, I've started building a small library which implements automatic simplification of C# expressions: https://github.com/dharmatech/Symbolism I guess this is mostly off-topic, so sorry about that. I wanted to mention the library here because GiNaC has been hugely influential (as has SymbolicC++). It's a very limited library, but I think it might be useful for someone wanting to experiment with building GiNaC type functionality in C# without starting from scratch. Ed

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