FUNCTION:  Iprod - inner product of vectors ,    
CALLING SEQUENCE:  Iprod(u,v);,    
PARAMETERS:  u,v = linear combinations of e1,e2,...,SYNOPSIS:   
  A "vector" (distinct from the vector data Structure used by Maple) is a
  linear combination of the standard orthonormal basis e1,e2,e3,..., with
  coefficients that are rational or floating-point.
  If u and v are vectors, Iprod(u,v) returns the inner product of u and v.

  While u must have coefficients that are rational or floating-point, this
  requirement is not necessary for v. All that is required for v is that
  the function calls  coeff(v,e1),coeff(v,e2),...  return valid answers. 
EXAMPLES:   ,  Iprod(e1+e2,e1-2*e2+e3);           yields       -1
  Iprod(e1+e2,a*e1+b*e2+c*e3);       yields       a+b
  r:=HighestRoot(D4);
  map(Iprod,Base(D4),r);             yields   [0, 0, 1, 0],    
SEE ALSO:  Reflect, RootCoords, Weyl[WeightCoords]):
