%
% Polynomial subtraction  h = f - g
%
% Syntax:  >> h = PolynomialPlus(f,g)
%     or:  >> h = pplus(f,g)
%
%   Input:    f --- (string or numeric) polynomial one
%             g --- (string or numeric) polynomial two
%
%  Output:    h --- (string) difference f-g
%
%  Example:  >> PolynomialMinus('5*x^2*y+8','3*x^2*y+2')
%
%            ans =
%
%            6 + 2*x^2*y
