Function: matintersect
Section: linear_algebra
C-Name: intersect
Prototype: GG
Help: matintersect(x,y): intersection of the vector spaces whose bases are
the columns of x and y.
Doc: $x$ and $y$ being two matrices with the same
number of rows each of whose columns are independent, finds a basis of the
$\Q$-vector space equal to the intersection of the spaces spanned by the
columns of $x$ and $y$ respectively. The faster function
\tet{idealintersect} can be used to intersect fractional ideals (projective
$\Z_K$ modules of rank $1$); the slower but much more general function
\tet{nfhnf} can be used to intersect general $\Z_K$-modules.