  The isodynamic points of a plane triangle are known to be the only pair of
its centers invariant under the action of the Mobius group on the set of
triangles. Generalizing this classical result, we introduce below the
isodynamic map associating to a univariate polynomial of degree d at least 3
with at most double roots a polynomial of degree (at most) 2d-4 such that this
map commutes with the action of the Mobius group on the zero loci of the
initial polynomial and its image. The roots of the image polynomial will be
called the isodynamic points of the preimage polynomial. Our construction
naturally extends from univariate polynomials to binary forms and further to
their ratios.
