function p = polynom(a)
%POLYNOM 為多項式類 polynom 的引導函數，它可以將其它形式
%給出的多項式變換成多項式類的形式。

%Designed by Prof D Xue (c) 2000
if nargin == 0
   p.c = [];
   p = class(p,'polynom');
elseif isa(a,'polynom')
   p = a;
else
   p.c = a(:).';
   p = class(p,'polynom');
end