Karim Belabas on Fri, 04 Sep 2009 13:53:05 +0200

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Re: [PATCH] short help typos

* Bill Allombert [2009-09-04 12:57]:
> On Fri, Sep 04, 2009 at 10:33:56AM +0200, Jeroen Demeyer wrote:
> > Bill Allombert wrote:
> >> I commited the two first in revision 11892.  The last one does not seem
> >> necessary.  Thanks for fixing this error!
> >
> > Of course the last one is not strictly *necessary*.  However, I think it  
> > is useful to point that out.  Maybe it looks obvious to you, but imagine  
> > that you never used mathnf() and you're looking for a way of adding  
> > Z-modules.
> > Compare also with ??idealintersect.
> If we want to document how to deal with Z-modules in PARI, probably we
> should add a dedicated section on this topic instead of adding bits
> of information in unrelated functions help messages. 

It's a useful caveat: idealadd can't handle arbitrary free Z-modules,
even though, from the user point of view, O_K-modules and free Z-modules
of the right rank are hard to distinguish (accordingly, nfisideal is
not a trivial function).

I included that information within a (long) example adressing other
issues. That should make everybody happy :-).

Possibly this can be expanded into a dedicated section (or the
tutorial), but it definitely belongs in the 'idealadd' help.

> By the way, ??matintersect still assume that idealintersect can handle
> free Z-modules. It should be updated.


Thanks !

Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite Bordeaux 1          Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux1.fr/~belabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux1.fr/  [PARI/GP]