Re: forqfvec

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

On Wed, Mar 28, 2012 at 09:52:36AM -0500, Ariel Pacetti wrote:
> 
> Dear pari developers,
> 
> sometime ago Bill wrote a routime called forqfvec which is a mix of
> qfminim and somehow forvec (see
> http://pari.math.u-bordeaux.fr/archives/pari-dev-1005/msg00003.html).
> 
> The advantage of such routine is that instead of giving the whole
> output of qfminim (which might blow up the memory) it lets you
> manage each vector at a time and then discard it. The first
> application of it is the routine qfrep writen by Karim.
> 
> In such routine, one takes each vector of qfrep and compute its
> norm, and then puts a 1 in the right place of a vector. This gives
> the q-expansion of modular forms (of integral weight or half
> integral weight) which is quite useful. I was asked by Bill to make
> some lobby on this routine, so let me just mention some other
> applications of it so as to consider including it in the future
> releases.

Hello Ariel,

Karim has commited my patch in rev 29e443c6fb79037e2ccd65084c5180fbc4568e21.

Here the documentation:

forqfvec(v,q,b,expr):

   q  being  a  square  and  symmetric  matrix  representing a positive definite quadratic form,
evaluate expr for all vector v such that q(v) <= b.  The formal variable v runs through all such
vectors in turn.

   ? forqfvec(v, [3,2;2,3], 3, print(v))
   [0, 1]~
   [1, 0]~
   [-1, 1]~

Cheers,
Bill.