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Weird: symbol * ddq_i, my_ex.subs((*ddq_i)==0) my_ex.subs(*ddq_i==0) my_ex.subs(symbol(*ddq_i)==0) ??
by Javier Ros 27 Jul '11

27 Jul '11

Hello, Being symbol * ddq_i the following trivial simplifications my_ex.subs((*ddq_i)==0) my_ex.subs(*ddq_i==0) my_ex.subs(symbol(*ddq_i)==0) go wrong no correct substitution, in different ways but my_ex.subs(lst(symbol(*ddq_i)==0,*ddq_i==0)) and my_ex.subs(lst(symbol(*ddq_i)==0,(*ddq_i)==0)) go OK. Interestingly until now I was simplifying correctly using my_ex.subs((*ddq_i)==0) I think this is not correct behavior. What's your opinion?. I suppose that my current expresion is more complex than it used to be, that's why. I have not experienced this before. I'm using Ubuntu 10.04 LTS provided GiNaC, Synaptic tells 1.5.5 -1. Thank you, Javier

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problem parsing "{"
by Jan Piclum 26 Jul '11

26 Jul '11

Hi, I have a problem when I try to create expressions containing harmonic polylogarithms from strings. The example program (based on section 5.15.2 of the tutorial) #include <ginac/ginac.h> int main() { GiNaC::symbol x; GiNaC::symtab table; table["x"] = x; GiNaC::parser reader(table); GiNaC::ex e = reader("H({0},x)"); std::cout << e << std::endl; } terminates with the message terminate called after throwing an instance of 'GiNaC::parse_error' what(): GiNaC: parse error at line 0, column 0: unexpected token, got: "{" [GiNaC::ex GiNaC::parser::parse_primary()(parser/parser.cpp:161)] However, using the H({0},x) in ginsh works fine. I am using GiNaC version 1.6.1 on a 32bit Linux PC running openSUSE 11.3. The program was compiled with g++ version 4.5.0. Is this a bug or is this syntax for lists no longer supported? Thanks for your help. Best regards, Jan Piclum.

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Bug Report
by Jon Graves 22 Jul '11

22 Jul '11

OS: Ubuntu 11.04 Compiled with g++: g++ -o test test.cpp -lcln -lginac GiNaC ver: 1.60 Sample version of program attached. My program is only meant to simplify expressions that resemble this form: (x^n)^(1/n) = x This program is using a particular value of n to demonstrate what I believe to be a bug (n=2). Two similar methods are employed to attempt to simplify the expression, using wildcards, but only the first one works, while the second doesn't. The second one is the most general one, useful for any situation ... if it worked. Is this a bug? ~Jon

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Bug Report
by Jon Graves 20 Jul '11

20 Jul '11

OS: Ubuntu 11.04 Compiled with g++: g++ -o test test.cpp -lcln -lginac GiNaC ver: 1.60 Sample version of program attached. Program generates Hermite polynomial to high degree. It then subs into it a series of numbers. The output RANDOMLY generates an incorrect answer. No answer after a substitution should ever be zero, yet zeros inevitably appear. The problem occurs once out of every 3 executions, on average.

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Release 1.6.1
by Jens Vollinga 18 Jul '11

18 Jul '11

Hi everybody, GiNaC 1.6.1 is out and available. The changes are the following: * Fixed several internal assertions for the debug version of GiNaC. * More verbose report of (auto-)configuration problems. * Fixed a compile problem with ginsh using gcc 4.6. As always, this release can be downloaded from http://www.ginac.de/Download.html Regards, Jens

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3 index tensors
by Gregory Stiesberg 09 Jul '11

09 Jul '11

Hello, Given a matrix of expressions A and vectors q,v,w, I'm trying to evaluate a tensor expression of the type diff(A_ij, q_k) * v_k * w_j . With i,j,k of type idx, and A,q of type Matrix, It would be nice to get a 3 index tensor from indexed( diff(A(i,j),q(k)), i,j,k) or by diff(indexed(A,i,j),indexed(q,k)) but these don't work. After looking at the definition of epsilon_tensor the simplest option seems to be to write a class indexed_from_function3 able to return a 3-index tensor from an arbitrary function of three indices: for example ex f(int i, int j, int k){ return( diff(A(i,j),q(k)) ); } ex tensexp0=indexed_from_function3(f, i,j,k) * indexed(v, k) * indexed(w, j) Is there already a way to construct an arbitrary 3-index tensor that I've not found yet? Thanks in advance, Gregg Stiesberg

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Subresultant calculation
by Joachim Redies 07 Jul '11

07 Jul '11

Hello everbody, is it possible to calculate the subresultant of two multivariate polynomials (inherited from ex) with little development effort and knowledge about the mathematical background? I have seen that sr_gcd in normal.cpp uses subresultants. Is it possible to isolate the subresultant calulation? Thanks, Joachim

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Windows build
by Kraus Philipp 02 Jul '11

02 Jul '11

Hello, I would like to use Ginac under Windows (with Visual Studio). Is there a build script like cmake to build the Ginac library? I have build Ginac with cygwin but in my opinion I can't link again the cygwin binaries with VS, because the linker creates different calls, so if I use Ginac with VS I must create the binary with VS Thanks Phil

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issues with ginac-1.6.0
by PG CLARK 25 May '11

25 May '11

this is probably me having installed the new library wrong but when I run my newly compiled program I get this error message ./main: error while loading shared libraries: libginac.so.2: cannot open shared object file: No such file or directory any ideas what might be the problem? I ran the make check after installing and it passed fine? regards peter clark ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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Re: [GiNaC-list] issues with ginac-1.6.0
by PG CLARK 25 May '11

25 May '11

Please disregard that. It was a bug in ubuntu 11 that just got fixed. That's the good news. Bad news is my program still gets killed for over use of ram and swap space. Are you really sure 1.6.0 has the improvement to simplified index in them? Tell me do we have an algorithm for taking 2 symetry trees acting on the same indexes and merging them to create one with the symetrys of both? If we had that I'm pretty sure I could write a far more efficient simplification algorithm. Quoting Stephen Montgomery-Smith <stephen(a)missouri.edu>: > You probably need to do > > sudo ldconfig > > PG CLARK wrote: >> Sorry thats a school boy error yes I'm running ubuntu 11.4, kernal >> 2.6.38-8-generic, gnome 2.32.1 (yes most of this isn't relevant but >> I'm going for completeness) >> >> 1.9GiB ram, AMD Athlon 64 X2 dual core processor >> >> ginac 1.6.0 was installed with the standard install commands included >> in the install file >> ./configure >> make >> sudo make install >> make check >> >> all tests passed >> >> my terminal after I tried ldconfig looked like this. >> >> peter@peter-ubuntu:~$ man ldconfig >> peter@peter-ubuntu:~$ ldconfig >> /sbin/ldconfig.real: Can't create temporary cache file >> /etc/ld.so.cache~: Permission denied >> peter@peter-ubuntu:~$ cd Documents >> peter@peter-ubuntu:~/Documents$ gcc main.cpp -o main -lcln -lginac >> peter@peter-ubuntu:~/Documents$ ./main >> ./main: error while loading shared libraries: libginac.so.2: cannot >> open shared object file: No such file or directory >> >> For give me but prior to using this system all I did was a bit of >> darwin tinkering and before that MS-dos. I'm not too clear on the >> specifics of how linux handles it's libraries. >> >> Quoting "Richard B. Kreckel"<kreckel(a)ginac.de>: >> >> >>> You didn't tell us about your system or how and where you installed >>> the library. Buy maybe you do have to run ldconfig? >>> >>> -richy. >>> -- >>> Richard B. Kreckel >>> <http://www.ginac.de/~kreckel/> >>> _______________________________________________ >>> GiNaC-list mailing list >>> GiNaC-list(a)ginac.de >>> https://www.cebix.net/mailman/listinfo/ginac-list >>> >>> >> >> >> ---------------------------------------------------------------- >> This message was sent using IMP, the Internet Messaging Program. >> >> >> _______________________________________________ >> GiNaC-list mailing list >> GiNaC-list(a)ginac.de >> https://www.cebix.net/mailman/listinfo/ginac-list >> >> >> >> > > ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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