  We describe a functional method to obtain the exact evolution equation of the
effective action with a parameter of the bare theory. When this parameter
happens to be the bare mass of the scalar field, we find a functional
generalization of the Callan-Symanzik equations. Another possibility is when
this parameter is the Planck constant and controls the amplitude of the
fluctuations. We show the similarity of these equations with the Wilsonian
renormalization group flows and also recover the usual one loop effective
action.
