-------- Original Message -------- Subject: Re: Type gen Date: Thu, 16 Oct 2003 18:01:00 +0200 From: "bernard.parisse" parisse@mozart.ujf-grenoble.fr To: Tatiana Zolo zolo@cs.unipr.it References: 3F8EC720.CC99C648@cs.unipr.it

Tatiana Zolo wrote:

Hi, my problem is the following and it can be split in 3 parts:

1. transform my object (expressions of various types) in a giac object
2. factorize the giac object
3. come back to my object.

I know how to do the problem 2): I used the type `gen' and the functions in the file sym2poly.{h,cc}.

About the problems 1) and 2) I did something in both the directions but I want ask you the best method to decompose a type gen. For example, if I have `g' of the type gen, where g = a + b + c + d, how can I consider the single summands? The same problem with a product of gen, a power of gen, ... How can I know if `g' is a sum of gen? Or a product of gen? I did not find these methods in the file gen.h. Is there documentation about these topics?

Hi!

There is preliminary documentation in info format, if you installed giac by make install, you should have it in /usr/local/info (in emacs Ctrl-U Ctrl-H I followed by /usr/local/info/giac.info should open it). Alternatively the HTML translated file is on my web site. For your question, a gen g that is a sum or a product or any kind of symbolic function applied to arguments is such that g.type==_SYMB and g._SYMBptr->sommet is the operator or function, g._SYMBptr->feuille is the argument (if the function is unary) or the vector of arguments (if the function has more than 1 arg). You can check the function either by g._SYMBptr->sommet== at_plus (for +) or at_prod (for *) or any other operator, or by g.is_symb_of_sommet(at_plus) For exemple if g=a+b+c+d if (g.is_symb_of_sommet(at_plus)){ gen & arg=g._SYMBptr->feuille; if (arg.type==_VECT){ vecteur & v= *arg._VECTptr; int s=v.size(); // number of args ... } }

bye!