% -*- texinfo -*-
% @deftypefn {Function File} {@var{q} =} polygcd (@var{b}, @var{a}, @var{tol})
%
% Find greatest common divisor of two polynomials. This is equivalent
% to the polynomial found by multiplying together all the common roots.
% Together with deconv, you can reduce a ratio of two polynomials.
% Tolerance defaults to
% @example
% sqrt(eps).
% @end example
% Note that this is an unstable
% algorithm, so don't try it on large polynomials.
%
% Example
% @example
% @group
% polygcd (poly(1:8), poly(3:12)) - poly(3:8)
% @result{} [ 0, 0, 0, 0, 0, 0, 0 ]
% deconv (poly(1:8), polygcd (poly(1:8), poly(3:12))) ...
% - poly(1:2)
% @result{} [ 0, 0, 0 ]
% @end group
% @end example
% @seealso{poly, polyinteg, polyderiv, polyreduce, roots, conv, deconv,
% residue, filter, polyval, polyvalm}
% @end deftypefn