Function: matrixqz
Section: linear_algebra
C-Name: matrixqz0
Prototype: GG
Help: matrixqz(x,p): if p>=0, transforms the rational or integral mxn (m>=n)
 matrix x into an integral matrix with gcd of maximal determinants equal to 1
 if p is equal to 0, not divisible by p otherwise. If p=-1, finds a basis of
 the intersection with Z^n of the lattice spanned by the columns of x. If
 p=-2, finds a basis of the intersection with Z^n of the Q-vector space
 spanned by the columns of x

