%C_1.m
y_zadane = 1;
[parametry, blad] = fminsearch('minimalizuj', [8.0, 490.0, 3.0]);

%minimalizuj.m
function blad = minimalizuj(X0)
    global y_zadane;
    Kp = X0(1);
    Ti = X0(2);
    Td = X0(3);
    [licz, mian] = zp2tf([], [-1, -1, -1], 1);
    G = tf(licz, mian);
    pid = pidstd(Kp, Ti, Td);
    G_sys = series(pid, G);
    y = step(G_sys);
    e = y - y_zadane;
    blad = sum(((e.^2)/length(e)));
end