Function: setintersect
Section: linear_algebra
C-Name: setintersect
Prototype: GG
Help: setintersect(x,y): intersection of the sets x and y.
Description:
 (vec, vec):vec        setintersect($1, $2)
Doc: intersection of the two sets $x$ and $y$ (see \kbd{setisset}).
 If $x$ or $y$ is not a set, the result is undefined.