function [type majority singular] = uniformity(x)
%[type majority singular] = uniformity(x)
%  checks uniformity of vector x and returns
%  1 when x is uniform (or all elements are the same),
%  2 when x is uniform except for a single element with a different value,
%  or 3 when x is multiform (contains three or more values).
%  In the cases of 1 and 2, the value of the majority is returned. In the case
%  of 2, the value of the singular element is also returned.
% (ja.doukaku.org Q53)
majority = -1; singular = -1;
r = unique(x);
h = histc(x,r);
[hs k] = sort(h,'descend');
type = length(r);
if type==1
    majority = r(k(1));
elseif type==2 && hs(2)==1
    majority = r(k(1));
    singular = r(k(2));
else
    type = 3;
end