function [t, y] = euler_k3_z2 (N, delta, y1, yz, his, t1)
    t = zeros(1,N/delta);
    t(1) = t1;
    y = zeros(1,N/delta);
    y(1) = y1;
    u1 = yz+1;
    u2 = yz-1;
    u = u1;
    for i = 1:(N/delta)
        uchyb = yz - y(i);
        if uchyb > his/2
            u = u1;
        end
        if uchyb < -his/2
           u = u2;
        end
        y(i+1) = y(i) + delta * ((-3)*y(i) + 3*u);
        t(i+1) = t(i) + delta;
    end
end