Function: sumdedekind
Section: number_theoretical
C-Name: sumdedekind
Prototype: GG
Help: sumdedekind(h,k): Dedekind sum attached to h,k.
Doc: returns the \idx{Dedekind sum} attached to the integers $h$ and $k$,
  corresponding to a fast implementation of
  \bprog
   s(h,k) = sum(n = 1, k-1, (n/k)*(frac(h*n/k) - 1/2))
  @eprog
