function s = char(p)
% POLYNOM/CHAR   
% CHAR(p) 是串表示的p.c
if all(p.c == 0)
    s = '0';
else
    d = length(p.c) - 1;
    s = [];
    for a = p.c;
        if a ~= 0;
            if ~isempty(s)
                 if a > 0
                     s = [s ' + '];
                     else
                     s = [s ' - '];
                     a = -a;
                 end
            end
            if a ~= 1 | d == 0
                 s = [s num2str(a)];
                 if d > 0
                     s = [s '*'];
                 end
            end
            if d >= 2
                 s = [s 'x^' int2str(d)];
                 elseif d == 1
                 s = [s 'x'];
            end
        end
        d = d - 1;
    end
end