Hi!,

I would like to know how to solve an issue I have with the root locus plot.

This is my code

NUM{1,1}=[-15,-300];

DEN{1,1}=[1,0];

G_idref_vdcref = tf(NUM{1,1},DEN{1,1});

rlocus(G_idref_vdcref);

hold on

n_idref_vdcref=roots(NUM{1,1})

d_idref_vdcref=roots(DEN{1,1})

plot(real(n_idref_vdcref),imag(n_idref_vdcref),"co","markersize",15)

plot(real(d_idref_vdcref),imag(d_idref_vdcref),"rx","markersize",15)

And the resulting root locus plot is:

<

http://octave.1599824.n4.nabble.com/file/t372684/rlocusplot1.jpg>

which is obviously incorrect, since in my transfer function there is a pole at

s=0 and a zero at s=-20, and in the picture we see that the rlocus line goes

to instability and other areas that it is not supposed to go. If I zoom the

rlocus plot we see:

<

http://octave.1599824.n4.nabble.com/file/t372684/rlocusplot2.jpg>

Where the zero and the pole are correctly located, however the connecting

line between them is incorrect. Any suggestion to solve this error?

Thanks.

--

Sent from:

http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html