algmakeintegral

Function: algmakeintegral
Section: algebras
C-Name: algmakeintegral
Prototype: GD0,L,
Help: algmakeintegral(mt,{maps=0}): computes an integral multiplication table
 for an isomorphic algebra.
Doc: \var{mt} being a multiplication table over $\Q$ in the same format as the
 input of \tet{algtableinit}, computes an integral multiplication table
 \var{mt2} for an isomorphic algebra. When $\var{maps}=1$, returns a \typ{VEC}
 $[\var{mt2},\var{S},\var{T}]$ where \var{S} and \var{T} are matrices
 respectively representing the map from the algebra defined by \var{mt} to the
 one defined by \var{mt2} and its inverse.
 \bprog
 ? mt = [matid(2),[0,-1/4;1,0]];
 ? algtableinit(mt);
   ***   at top-level: algtableinit(mt)
   ***                 ^----------------
   *** algtableinit: domain error in algtableinit: denominator(mt) != 1
 ? mt2 = algmakeintegral(mt);
 ? al = algtableinit(mt2);
 ? algisassociative(al)
 %4 = 1
 ? [mt2, S, T] = algmakeintegral(mt,1);
 ? S
 %6 =
 [1   0]

 [0 1/4]
 ? T
 %7 =
 [1 0]

 [0 4]
 ? vector(#mt, i, S * (mt * T[,i]) * T) == mt2
 %8 = 1
 @eprog