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- par lukamar
- lun. juil. 08, 2019 8:20 pm
- Forum : Giac
- Sujet : Gamma(n) = (n-1)!
- Réponses : 3
- Vues : 2654
Thanks for the code, it's really a simple solution, but I do not know about possible side effects either. Perhaps it's better to leave the simplification to individual commands than doing it automatically.
- par lukamar
- lun. juil. 08, 2019 10:47 am
- Forum : Giac
- Sujet : Gamma(n) = (n-1)!
- Réponses : 3
- Vues : 2654
Hello, Giac does some simplifications of sin(n*pi) and cos(n*pi) after assume(n,integer). I propose a similar simplification for the gamma function, i.e. that Gamma(n) returns (n-1)! when n is a symbol assumed to be a positive integer. Something similar could also be done with the Beta function, as ...
- par lukamar
- mar. juin 18, 2019 8:35 pm
- Forum : Giac
- Sujet : domain and about
- Réponses : 2
- Vues : 2445
Hello, I think that 'domain' command should intersect its result with the set obtained by 'about' command (the real case). For example, when entering assume(x<1); domain(ln(x),x) one obtains x>0, but shouldn't it be x>0 and x<1? Also, by doing the intersection domain(x) would return x<1, i.e. the do...
- par lukamar
- dim. mai 12, 2019 5:44 pm
- Forum : Giac
- Sujet : defininig periodic functions
- Réponses : 4
- Vues : 4904
Hello Bernard, I noticed a bug in periodic command. On the line 6195 in intg.cc there is a check if (e.type!=_SYMB) return gentypeerr(contextptr); It should be removed (i.e. lines 6195-6196 deleted) because it prevents entering e.g. x as the first argument. By the way, I also coded a better implemen...
- par lukamar
- ven. mars 08, 2019 2:42 pm
- Forum : Giac
- Sujet : graph theory commands for Giac
- Réponses : 198
- Vues : 62311
New updates: * traveling_salesman now works with digraphs too, I also improved the code for undirected graphs, * hamiltonicity testing for digraphs is improved, * imported graphs are now checked for duplicate vertex labels, * graph theory manual is updated and I corrected/added some examples in aide...
- par lukamar
- jeu. févr. 28, 2019 10:21 am
- Forum : Giac
- Sujet : graph theory commands for Giac
- Réponses : 198
- Vues : 62311
Hi, I have improved is_hamiltonian command, now it uses a backtracking algorithm and works with digraphs as well as with undirected graphs. It does not call traveling_salesman anymore. The backtracking technique is simple but it works well on smaller graphs. I changed the corresponding entry in the ...
- par lukamar
- mar. févr. 26, 2019 5:15 pm
- Forum : Giac
- Sujet : nonlinear optimization functions
- Réponses : 77
- Vues : 46605
Thanks! Do you perhaps have deb files compiled with nauty and GLPK? Btw, I fixed couple of bugs in optimization.cc today. The command extrema has been having some problems with critical point classification which produced incorrect or not well defined results in some cases. Also, minimax was crashin...
- par lukamar
- ven. févr. 22, 2019 8:55 am
- Forum : Giac
- Sujet : nonlinear optimization functions
- Réponses : 77
- Vues : 46605
Can't reproduce the crash with extrema(x*y*z,x^2+y^2+z^2=1,[x,y,z]) on ubuntu in 1.5.0-43. It's working fine now. By the way, there is incompatibility between giac and ubuntu 18.04, I had to install couple of deb packages by hand (libreadline6, for example). That was on a clean ubuntu install with g...
- par lukamar
- lun. févr. 18, 2019 11:12 am
- Forum : Xcas - English
- Sujet : some problem with determinant of a matrix
- Réponses : 4
- Vues : 2106
Hello Jose,
I think that mixing approx values with symbols is the problem here, but Bernard will know better. As a workaround, I propose applying "exact" before computing the determinant:
Luka
- par lukamar
- ven. févr. 15, 2019 7:34 pm
- Forum : Giac
- Sujet : graph theory commands for Giac
- Réponses : 198
- Vues : 62311
I made another small fix, this time in graphe::adjacent_nodes (duplicate vertex entries were produced). graphtheory.cc is also updated.
- par lukamar
- ven. févr. 15, 2019 6:09 pm
- Forum : Giac
- Sujet : graph theory commands for Giac
- Réponses : 198
- Vues : 62311
There should be changes at lines 1148, 1176 and 1180 in graphtheory.cc. I pushed another commit today fixing a small bug in graphe.cc (line 2260 is inserted). I see those changes in my github repository. Try pulling it again, maybe it will work this time.
- par lukamar
- jeu. févr. 14, 2019 2:28 pm
- Forum : Giac
- Sujet : graph theory commands for Giac
- Réponses : 198
- Vues : 62311
Hi,
I have committed a small fix for has_arc command. It hasn't been accepting vertex types other than integer.