FUNCTION: LieTools/Eip
USAGE: Eip(i,j);
SYNOPSIS: Eip(i,j) computes the inner products of root vectors 
   indexed by the integers i and j (i and j should be non-zero
   integers between -nprts and nprts).
CAVEATS: requires a previously initialized global Lie algebra environment.
  (See LieTools[gSetup].)
EXAMPLE: 
> LieTools[gSetup](G,2);
Setting up Gtype = G   rnk = 2
> LieTools[Eip](1,1);

                                  2

> LieTools[Eip](1,2);

                                  -3

> LieTools[Eip](2,2);

                                  6

SEE ALSO: Coxeter[Iprod]
