## Full example

    function mandel(z)
        c = z
        maxiter = 80
        for n = 1:maxiter
            if abs(z) > 2
                return n-1
            end
            z = z^2 + c
        end
        return maxiter
    end

    function randmatstat(t)
        n = 5
        v = zeros(t)
        w = zeros(t)
        for i = 1:t
            a = randn(n,n)
            b = randn(n,n)
            c = randn(n,n)
            d = randn(n,n)
            P = [a b c d]
            Q = [a b; c d]
            v[i] = trace((P.'*P)^4)
            w[i] = trace((Q.'*Q)^4)
        end
        std(v)/mean(v), std(w)/mean(w)
    end