Function: serconvol
Section: polynomials
C-Name: convol
Prototype: GG
Help: serconvol(x,y): convolution (or Hadamard product) of two power series.
Doc: convolution (or \idx{Hadamard product}) of the
 two power series $x$ and $y$; in other words if $x=\sum a_k*X^k$ and $y=\sum
 b_k*X^k$ then $\kbd{serconvol}(x,y)=\sum a_k*b_k*X^k$.