Function: alginv
Section: algebras
C-Name: alginv
Prototype: GG
Help: alginv(al,x): element 1/x in al.
Doc: Given an element $x$ in \var{al}, computes its inverse $x^{-1}$ in the
 algebra \var{al}. Assumes that $x$ is invertible.
 \bprog
 ? A = alginit(nfinit(y), [-1,-1]);
 ? alginv(A,[1,1,0,0]~)
 %2 = [1/2, 1/2, 0, 0]~
 @eprog

 Also accepts matrices with coefficients in \var{al}.
