Function: qfperfection
Section: linear_algebra
C-Name: perf
Prototype: G
Help: qfperfection(G): rank of matrix of xx~ for x minimal vectors of a gram
 matrix G.
Doc:
 $G$ being a square and symmetric matrix with
 integer entries representing a positive definite quadratic form, outputs the
 perfection rank of the form. That is, gives the rank of the family of the $s$
 symmetric matrices $v_iv_i^t$, where $s$ is half the number of minimal
 vectors and the $v_i$ ($1\le i\le s$) are the minimal vectors.

 Since this requires computing the minimal vectors, the computations can
 become very lengthy as the dimension of $x$ grows.
