Function: algsub
Section: algebras
C-Name: algsub
Prototype: GGG
Help: algsub(al,x,y): element x-y in al.
Doc: Given two elements $x$ and $y$ in \var{al}, computes their difference
$x-y$ in the algebra \var{al}.
\bprog
? A = alginit(nfinit(y), [-1,-1]);
? algsub(A,[1,1,0,0]~,[1,0,1,0]~)
%2 = [0, 1, -1, 0]~
@eprog
Also accepts matrices with coefficients in \var{al}.