  By writing the flow equations for the continuum Legendre effective action
(a.k.a. Helmholtz free energy) with respect to a particular form of smooth
cutoff, and performing a derivative expansion up to some maximum order, a set
of differential equations are obtained which at FPs (Fixed Points) reduce to
non-linear eigenvalue equations for the anomalous scaling dimension $\eta$.
Illustrating this by expanding (single component) scalar field theory, in two,
three and four dimensions, up to second order in derivatives, we show that the
method is a powerful and robust means of discovering and quantifying
non-perturbative continuum limits (continuous phase transitions).
