## La recherche a retourné 118 résultats

dim. janv. 28, 2018 3:41 pm
Forum : Giac
Sujet : Sample use of gbasis in C++
Réponses : 14
Vues : 3395

### Sample use of gbasis in C++

Hi, Is there anywhere I could see a minimal example of how I can compute groebner basis using giac in C++? For instance suppose I have a vecpoly consisting of generator of an ideal (say some katsura polynomial system) and now I want to use gbasis. I see that in solve.cc there is a method called giac...
mer. janv. 24, 2018 3:35 pm
Forum : Giacpy
Sujet : accessing some pari types
Réponses : 11
Vues : 3112

### Re: accessing some pari types

Thanks. Regarding the ntl issue and windows I can remind everyone about the link of the discussion (crash in factor if giac is linked with ntl in windows): http://xcas.e.ujf-grenoble.fr/XCAS/viewtopic.php?f=3&t=1901 What if I am able to compile giac with mpir, will the lack of ntl still make factor ...
mer. janv. 24, 2018 12:46 pm
Forum : Giacpy
Sujet : accessing some pari types
Réponses : 11
Vues : 3112

### Re: accessing some pari types

Well, there is a confusion in the meaning of t, your t is alpha=rootof([[1,0],[1,0,-3,1]]), rootof(P,M) where P and M are list polynomials means P(alpha) where M(alpha)=0 (M irreducible). The last command of Frederic is the list of factors of t^3-3t+1, i.e. t+(-alpha), t+(-alpha^2+2), t+(alpha^2+al...
mer. janv. 24, 2018 5:32 am
Forum : Giacpy
Sujet : accessing some pari types
Réponses : 11
Vues : 3112

### Re: accessing some pari types

Hi Frederic, Thank you for your answer. I do not understand the output of rootof, I do not see [t,t^2-2,-t^2-t+4] in the output of your sample code. Could you explain a bit? More generally, if f is a polynomial over Q (of arbitrary degree) such that the splitting field of f is Q(a) for some root "a"...
mar. janv. 23, 2018 12:57 pm
Forum : Giacpy
Sujet : accessing some pari types
Réponses : 11
Vues : 3112

### accessing some pari types

Hi, I want to know how to access some member variable of a pari type that comes out of giac/giacpy. Here is an example: from giacpy import giac giac("printpow(1)") giac("pari()") nfinit = giac("nfinit") galoisinit = giac("galoisinit") f = giac("t^3-3*t+1") #splitting field has primitive element whic...
ven. janv. 19, 2018 10:12 am
Forum : Giacpy
Sujet : giacpy 0.6.4
Réponses : 13
Vues : 6316

### Re: giacpy 0.6.4

Hi Frederic, Thanks for the update. Is there already a fix on matrix initialization (deep copy vs. shallow copy of matrix elements) in this version of giacpy? I am talking about having to initilaize matrices by mat = matrix(3,3) instead of mat = matrix(3,3,'(u,v)->0')) because of a bug in initializa...
mar. janv. 02, 2018 12:59 pm
Forum : Giac
Sujet : lacking features that is clearly used in grobner basis
Réponses : 2
Vues : 1525

### Re: lacking features that is clearly used in grobner basis

Oh nice. So if I put in the ordering as a third parameter I actually get the leading term (not only the leading coefficient) with respect to the that ordering. I couldn't have guessed (I don't think it was also in the manual, but I have an older pdf version of the manual). Thanks and sorry for the d...
mar. janv. 02, 2018 10:30 am
Forum : Giac
Sujet : lacking features that is clearly used in grobner basis
Réponses : 2
Vues : 1525

### lacking features that is clearly used in grobner basis

Hi, I was wondering if there is really no way to get leading term monomial list from a list of (multivariate) polynomials such as? Or apply monomial ordering (of certain ordering type, e.g. plex, tdeg etc.) to a certain polynomial I am sure these features (maybe hidden internally) exists in giac but...
lun. janv. 01, 2018 9:04 pm
Forum : Giacpy
Sujet : problems when using degree on indeterminates with indices
Réponses : 1
Vues : 1295

### problems when using degree on indeterminates with indices

Hi, I noticed the following problem from giacpy import degree degree("x1**2") degree("x**2") The first will return 0, the second will return 2. Although giac recognizes the expressions properly i.e. when doing arithmetic the indeterminate x1 will behave as it should. This behaviour also exists in Xc...
mer. déc. 27, 2017 10:20 am
Forum : Giacpy
Sujet : Getting the monomials of a polynomial
Réponses : 4
Vues : 1494

### Getting the monomials of a polynomial

Hi, What is the easiest (and not very slow) way to get a list of monomials of a polynomial. For instance if I have 3x*y+3x^2+y I want the list [3x*y,3x^2,y]. I can write a code that takes the total degree and walks through all possible monomial not exceeding this degree, but this will not be efficie...
ven. déc. 22, 2017 9:18 am
Forum : Giacpy
Sujet : gramschmidt is missing in giacpy
Réponses : 1
Vues : 1390

### gramschmidt is missing in giacpy

Hi, I just want to report that gramschmidt is missing in giacpy. Edit: I got it working using the same trick Frederic taught me for using randseed (basically calling it using giac, so you can enclose "gramschmidt" in giac instead of Pygen) from giacpy import Pygen, ranm gramschmidt = Pygen("gramschm...
jeu. déc. 21, 2017 7:07 pm
Forum : Giac
Sujet : generating random numbers, vectors, etc. and random seed
Réponses : 2
Vues : 1410

### Re: generating random numbers, vectors, etc. and random seed

Thanks Frederic. This worked. Now I can rely on the randomizer.
jeu. déc. 21, 2017 5:34 am
Forum : Giacpy
Sujet : random seed
Réponses : 0
Vues : 1518

### random seed

Hi Frederic,

I would like to point your attention to the following post:
http://xcas.e.ujf-grenoble.fr/XCAS/view ... f=4&t=1968

I think you answered my other posts but this post got lost between other posts. I believe that randseed is behaving differently than it should in giacpy.

Jose
mer. déc. 20, 2017 5:10 am
Forum : Giac
Sujet : Some questions about gen class
Réponses : 5
Vues : 2263

### Re: Some questions about gen class

Hello Luka,

I am just half guessing. But isn't at_pointprod the Hadamard product? I haven't tried it myself but just looked at the C code.

Jose
mar. déc. 19, 2017 12:52 pm
Forum : Giac
Sujet : generating random numbers, vectors, etc. and random seed
Réponses : 2
Vues : 1410

### generating random numbers, vectors, etc. and random seed

Hi, How do you set the seed of the random number generator for giac. I want to specifically used ranm and rand but I get the impression that I am using randseed wrongly. from giacpy import randseed randseed(123) Edit: I realized that there is a bug in python that does not appear in Xcas. In Xcas, ra...