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binomial coefficients
by Marko Riedel 07 Feb '23

07 Feb '23

Greetings. I would like to point out that binomial(-5, -7) will produce a segmentation fault. Compare to Maple which says that when binomial(n,k) has k<0 but n-k>=0 we should use binomial(n, n-k) which gives 15 in this case. Best regards, Marko

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Segmentation Fault when calculate cos(cos(1/2))
by 翁湛阳 07 Feb '23

07 Feb '23

Dear GiNaC Team, When I tried to use GiNaC to calculate cos(cos(1/2)),I got a Segmentation Fault. My environment is as following: CPU: Intel i7-10750H Windows10 21H2 gcc version 12.2.0 (MinGW-W64 x86_64-ucrt-posix-seh) GiNaC 1.8.5 CLN 1.3.6 GMP 6.2.1 ArchLinux(in VMwave) Kernel: 6.1.9-arch1-1 GiNaC 1.8.4 installed by pacman CLN 1.3.6 installed by pacman gcc version 12.2.1 20230111(GCC) Relative code file is attached The program crash at line 8.I tried to compile and run the same program at ArchLinux(GCC 12.2.1 GiNaC 1.8.4 CLN 1.3.6),and also got a segmentation fault. Besides , I tried to use ginsh to execute “cos(cos(1/2));” in ArchLinux ,it gave a error: Internal error: statement in file float/misc/cl_F_extendsqrt.cc, line 30 has been reached!! The same error also occurred at Windows,but it just exit without the information above. After that, I built some lower version of GiNaC in Windows10 and re-run my code.I found the bug disappeared at GiNaC 1.8.3 . After reading the commit history I rollback ginac\inifcns_trans.cpp to version 1.8.3 and rebuilt ,the bug disappeared. All my best, -Weng Zhanyang.

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subscripted variables
by Marko Riedel 06 Feb '23

06 Feb '23

Greetings to all. I am at this time considering to use GiNaC for some computations from group theory. I am not a C++ programmer. I would like to ask for assistance with the following task. I have a polynomial in several variables like a[1], a[2], a[5] etc. I understand I can initialize these by creating a symbol object with the variable name. The problem is, I need an easy and conformal means of accessing the integer in the variable name. This could be done by matching the name to a regular expression and extracting the value but I imagine there must be a better way. I am also looking for a means of extracting a set of variables that are present in a polynomial, or the degree these variables have. Furthermore, another question, does the C++ standard library have a means of memoizing functions? Thank you for your assistance. Marko Riedel

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GiNaC 1.8.5 released
by Richard B. Kreckel 01 Jan '23

01 Jan '23

Happy New Year! As in 2022, New Year's Day brings a new GiNaC release. The only change is in factor(): * Speed up multivariate polynomial factorization; fix it in some rare corner cases where it didn't previously terminate. ...and happy hacking! -richy. -- Richard B. Kreckel <https://in.terlu.de/~kreckel/>

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Failed Tests
by Robin Marzucca 21 Sep '22

21 Sep '22

Dear GiNaC Team, I just pulled the latest version of GiNaC from git and followed the installation steps as described. When running ‘make check’ I found two failed tests, the logs to which I attach. I just got a new laptop with an Apple Silicon processor, so the issue might still be related to that somehow, but most of the checks went through. Cheers, Robin

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GiNaC 1.8.4 released
by Richard B. Kreckel 19 Sep '22

19 Sep '22

Hi, GiNaC 1.8.4 has been tagged and released with some unplanned git noise. The News: * Complete the support for sqrfree_parfrac(). * Add info methods for transcendental functions. -richy. -- Richard B. Kreckel <https://in.terlu.de/~kreckel/>

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Potential issue in comparator in test_antipode
by Yuri Gribov 06 Jun '22

06 Jun '22

Hi, The comparison in `node::operator<` in time_antipode.cpp seems to be missing a dereference operation in return statement: if (!(*vert==*n.vert)) return (vert<n.vert); This causes the comparator to be non-transitive: (gdb) p *keys[5] < *keys[4] $5 = true (gdb) p *keys[4] < *keys[8] $6 = true (gdb) p *keys[5] < *keys[8] $7 = false which violates the strict weak ordering requirements of std::map (https://en.cppreference.com/w/cpp/named_req/Compare) Such violations may in practice result in non-deterministic behavior or crashes. The issue was found with [SortChecker++ tool](https://github.com/yugr/sortcheckxx). Best regards, Yuri Gribov

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GiNaC 1.8.3 released
by Richard B. Kreckel 24 Mar '22

24 Mar '22

Hi, GiNaC 1.8.3 has been tagged. The News: * series_to_poly() can be used from ginsh. * Fix power::to_polynomial() for posint exponents. * Fix power::subs() in some special cases. As always, happy hacking, and a lovely UN International Day for the Right to the Truth Concerning Gross Human Rights Violations and for the Dignity of Victims! (24 March) -richy. -- Richard B. Kreckel <https://in.terlu.de/~kreckel/>

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a counterintuitive case with subs
by Feng Feng 23 Mar '22

23 Mar '22

Dear all, I got a problem with the function subs, and I am not sure it is a possible bug or not, but it seems counterintuitive. Here is the code to reproduce the case: //------------------------------------------------ #include "ginac/ginac.h" using namespace std; using namespace GiNaC; int main() { symbol s("s"); ex t = subs(1/s,s==1/s, subs_options::no_pattern); cout << t << endl; return 0; } //------------------------------------------------ The output is 1/s instead of s. PS: if I remove the subs_options::no_pattern, the output is s as expected. and I have a look at the source code of basic::subs, it seems it comes from the following code: that is, the final substitutions on the new object as a whole, //------------------------------------------------ // Perform substitutions on the new object as a whole return copy->subs_one_level(m, options); //------------------------------------------------ Thanks very much in advance. Best regards! Feng

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Add series_to_poly to ginsh
by Vitaly Magerya 07 Feb '22

07 Feb '22

Hi, all. Could we add "series_to_poly" to ginsh? It would make operating on series easier; as it stands there's no way to discard the Order() term in ginsh. The patch is attached (does this list accept attachments?).

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