I wonder how to make the lines thicker in rlocus graph

Hello, I need your help, pleease.

I want to plot root locus graph. So, I use rlocus command, and I can get this graph.

command : rlocus(H1,'r',H2,'g',H3,'b',H4,'v')

But I don't this because this line is too thin.

I wish those graph lines (including unit circle) to be thicker.

I think of this way that I use hold and plot command to be thicker the lines.

But, I think there must be better way.

Please let me know how to make the lines thicker easily.

Answer 1

[Sam Chak]

Hi @jaejin kim

You can try this approach to make the lines of your loci thicker.

num = [1];
den = [1 4 5 0];
K   = 0:0.01:1000;
r   = rlocus(num,den,K);
plot(r, '-', 'LineWidth', 2); hold on
axis([-3 1 -2 2]); 
axis('square')
sgrid([0.5, 0.707], [0.5, 1,2])
grid, 
xlabel('Real Axis'), ylabel('Imag Axis'), title('Root Locus Plot')
p   = roots(den)    % open-loop poles

p = 
   0.0000 + 0.0000i
  -2.0000 + 1.0000i
  -2.0000 - 1.0000i

plot(real(p(1)), imag(p(1)), 'x', 'LineWidth', 2, 'MarkerSize', 12, 'color', '#77AC30')
plot(real(p(2)), imag(p(2)), 'x', 'LineWidth', 2, 'MarkerSize', 12, 'color', '#77AC30')
plot(real(p(3)), imag(p(3)), 'x', 'LineWidth', 2, 'MarkerSize', 12, 'color', '#77AC30')

[Frederick Just-Agosto]

Great response and very useful to understand the whole process, modified it to make my plots. Thanks

Answer 2

[KSSV]

sys = tf([2 5 1],[1 2 3]);
rlocus(sys)
set(findall(gca, 'Type', 'Line'),'LineWidth',5);

Answer 3

[Andrew Ouellette]

Starting in R2026a, you can do this directly from the rlocusplot command.

rlocusplot(rss(3),LineWidth=5)