  Given a straight-line program whose output is a polynomial function of the
inputs, we present a new algorithm to compute a concise representation of that
unknown function. Our algorithm can handle any case where the unknown function
is a multivariate polynomial, with coefficients in an arbitrary finite field,
and with a reasonable number of nonzero terms but possibly very large degree.
It is competitive with previously known sparse interpolation algorithms that
work over an arbitrary finite field, and provides an improvement when there are
a large number of variables.
