function r=discrnd(M,n)
%function r=discrnd(bins,n)
% sample n RVs from a discrete probability concentrated on [1..N] where
% the probability mass is proportional to the positive vector bins
%
% Guy Lebanon, 2004

cM=cumsum(M);
rr=unifrnd(0,cM(end),[1 n]);
for i=1:n,
    [tmp,ind] =  max(cM >= rr(i));
    r(i) = ind;
end