Function: algdim
Section: algebras
C-Name: algdim
Prototype: lG
Help: algdim(al): dimension of the algebra al.
Doc: Given a central simple algebra \var{al} output by \tet{alginit}, returns
 the dimension of \var{al} over its center. Given a table algebra \var{al}
 output by \tet{algtableinit}, returns the dimension of \var{al} over its prime
 subfield ($\Q$ or $\F_p$).
 \bprog
 ? nf = nfinit(y^3-y+1);
 ? A = alginit(nf, [-1,-1]);
 ? algdim(A)
 %3 = 4
 @eprog