function mu = cumcoherence(obj)
obj = normalize(obj);
[M N] = size(obj.phi);
mu = zeros(M,1);
for m=1:M
    c = zeros(N);
    for i=1:N
        c(:,i) = abs(obj.phi'*obj.phi(:,i));
        c(i,i) = 0;
    end
    c = sort(c,'descend');
    c = c(1:m,:);
    if m==1
        mu(m) = max(c);
    else
        mu(m) = max(sum(c));
    end
end
end
