Re: NULLs in gerepileall

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

On Sun, Jan 04, 2009 at 05:03:45PM +0100, Xavier-François Roblot wrote:
> Karim Belabas wrote:
> > * Xavier Roblot [2009-01-04 00:17]:
> >> Using gerepileall (and related memory management functions) on a vector
> >> containing some NULLs gives a SIGSEV (in the function taille0_nolist).
> >> Is there a way to solve this problem that does not require replacing
> >> NULLs by something else? I find it very convenient, for many reasons,
> >> to use NULLs in vectors...

Please always mentions "such reasons" if you would like us to take them
into account. We have no choice but to ignore unknown reasons.

> > 1) NULLs are not proper GENs, hence no object containing NULLs can be a
> > proper GEN; gerepile & friends are only guaranteed to work on proper
> > GENs. (As it happens, some gerepile functions do accept NULL as input
> > but this is undocumented and may not last.)
> 
> OK, I see. I have to say that it is very useful to have the possibility
> to set a GEN to NULL.

Simply use gnil instead of NULL. (GP2C use gen_0 for that purpose).

Cheers,
Bill.