  In these notes, we explain residue formulae for volumes of convex polytopes,
and for Ehrahrt polynomials based on the notion of total residue. We apply this
method to the computation of the volume of the Chan-Robbins polytope. The final
computation is based on a total residue formula for the system $A_n$, similar
to Morris identity. For flow polytopes, a formula of change of variables in
total residues leads to a "nice formula" for Ehrhart polynomials in function of
mixed volumes. We apply it to Pitman-Stanley polytope.
