polcoeff

[Ilya Zakharevich <ilya@math.ohio-state.edu>]

It looks like polcoeff() is silently converting a rational function
into a power series.  Is it a good thing to do?  I was very surprized
by this (my - wrong - algo did not produce any error, while silently
giving a wrong result).

The fact that it *can* operates on power series *is* mentioned in the
docs, but not in the docs for the function.  The fact that it would
coerce a "wrong" type is not mentioned at all...

Ilya