Karim BELABAS on Fri, 07 Nov 2003 19:57:34 +0100 |
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qfrep |
Dear pari-dev, I have applied a patch by Gonzalo Tornaria implementing a new routine qfrep(q, B, {flag = 0}): q being a square and symmetric matrix with integer entries representing a positive definite quadratic form, outputs the vector whose i-th entry, 1 <= i <= B is half the number of vectors v such that q(v) = i. This routine uses a naive algorithm based on qfminim, and will fail if any entry becomes larger than 2^{31}. The binary digits of flag mean: * 1: count vectors of even norm from 1 to 2B. * 2: return a t_VECSMALL instead of a t_GEN The library syntax is qfrep0(q, B, flag). Gonzalo needed it to identify the associated theta series, and it's rather less cumbersome than calling qfminim, storing all the minimal vectors and sorting the result by increasing norm. 'rep' stands for "representation". Does anybody see a better name ? Cheers, Karim. -- Karim Belabas Tel: (+33) (0)1 69 15 57 48 Dép. de Mathématiques, Bât. 425 Fax: (+33) (0)1 69 15 60 19 Université Paris-Sud http://www.math.u-psud.fr/~belabas/ F-91405 Orsay (France) http://pari.math.u-bordeaux.fr/ [PARI/GP]