Using rlocus I am confused

G = tf([1 1], conv([1 2 2], [1 2 5]));
rlocus(G, linspace(-8, 0, 1000), linspace(-10,10,1000))

Error using DynamicSystem/rlocus
Invalid syntax for time or frequency response command. See command help for more information.

title('Root Locus Diagram');
xlabel('Real Axis');
ylabel('Imaginary Axis');

Confused because it keeps giving me the same error and I am wondering if I need to format it differently or something

Answer 1

[Star Strider]

You appear to be overthinking it.

Try this —

G = tf([1 1], conv([1 2 2], [1 2 5]));

figure
rlocusplot(G)
grid

% title('Root Locus Diagram');
% xlabel('Real Axis');
% ylabel('Imaginary Axis');

The rlocusplot function has more options than rlocus, although it does not return the feedback gains. Use whatever of these functions you find best for your application.

.

Answer 2

[Paul]

Hi Madyson,

If you want to draw the root locus for a specific range of gains, then only specify a single range at a time

G = tf([1 1], conv([1 2 2], [1 2 5]));
figure
rlocus(G, linspace(-8, 0, 1000));
title('Root Locus Diagram');

xlabel('Real Axis');
ylabel('Imaginary Axis');

Or

G = tf([1 1], conv([1 2 2], [1 2 5]));
figure
rlocus(G, linspace(-10,10,1000));
title('Root Locus Diagram');

xlabel('Real Axis');
ylabel('Imaginary Axis');

Or, use rlocusplot, but as with rlocus only specify a single gain vector.