# I wonder how to make the lines thicker in rlocus graph

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jaejin kim on 5 Jan 2024
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.

Sam Chak on 5 Jan 2024
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 on 8 Feb 2024
Great response and very useful to understand the whole process, modified it to make my plots. Thanks

KSSV on 5 Jan 2024
sys = tf([2 5 1],[1 2 3]);
rlocus(sys)
set(findall(gca, 'Type', 'Line'),'LineWidth',5);