Function: ffmap
Section: number_theoretical
C-Name: ffmap
Prototype: GG
Help: ffmap(m, x): given a (partial) map m between two finite fields,
 return the image of x by m. The function is applied recursively to the
 component of vectors, matrices and polynomials. If m is a partial map that
 is not defined at x, return []
Doc: given a (partial) map $m$ between two finite fields, return the image of
 $x$ by $m$. The function is applied recursively to the component of vectors,
 matrices and polynomials. If $m$ is a partial map that is not defined at $x$,
 return $[]$.
 \bprog
 ? a = ffgen([3,5],'a);
 ? b = ffgen([3,10],'b);
 ? m = ffembed(a, b);
 ? P = x^2+a*x+1;
 ? Q = ffmap(m,P);
 ? ffmap(m,poldisc(P)) == poldisc(Q)
 %6 = 1
 @eprog
