Help with rlocus appearance of initial location of poles and zeros

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Help with rlocus appearance of initial location of poles and zeros

Beginner1
This post was updated on .
<http://octave.1599824.n4.nabble.com/file/t372684/rlocus.jpg
<http://octave.1599824.n4.nabble.com/file/t372684/rlocus_zoom.jpg> Hi,
I write this post to ask for help in increasing the markersize of the
initial location of the poles (x) and zeros (o) at the rootocus diagram.
This is my code:

/pkg control load
%ki=1;
kp=1.5;
w=314.159;

num=([kp ki kp*w.^2]);
den=([1 0 w.^2]);
sis=tf(num,den);


[RLDATA, ki] = rlocus (sis, 0.1, 0, 500);
%plot(rlocus(sis),"*","markersize",1)
rlocus(sis)
y=rlocus(sis,"marker","x","markersize",20)
%plot(rlocus(sis),"marker", "x", "markersize", 3, "linestyle",
"none","markerfacecolor", "blue");/

I have tried with different options of increasing the size of the plot but
none of them
produces any change in the plot. Attached you will find the figure.
Basically I want to increase the size of the red and green dots, but not the
blue line that connnect the poles with the zeros.

Thank you.

Best regards





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Re: Help with rlocus appearance of initial location of poles and zeros

Doug Stewart-4


On Fri, Jan 26, 2018 at 8:00 AM, Beginner1 <[hidden email]> wrote:
<http://octave.1599824.n4.nabble.com/file/t372684/rlocus.jpg>
<http://octave.1599824.n4.nabble.com/file/t372684/rlocus_zoom.jpg> Hi,
I write this post to ask for help in increasing the markersize of the
initial location of the poles (x) and zeros (o) at the rootocus diagram.
This is my code:

/pkg control load
%ki=1;
kp=1.5;
w=314.159;

num=([kp ki kp*w.^2]);
den=([1 0 w.^2]);
sis=tf(num,den);


[RLDATA, ki] = rlocus (sis, 0.1, 0, 500);
%plot(rlocus(sis),"*","markersize",1)
rlocus(sis)
y=rlocus(sis,"marker","x","markersize",20)
%plot(rlocus(sis),"marker", "x", "markersize", 3, "linestyle",
"none","markerfacecolor", "blue");/

I have tried with different options of increasing the size of the plot but
none of them
produces any change in the plot. Attached you will find the figure.
Basically I want to increase the size of the red and green dots, but not the
blue line that connnect the poles with the zeros.

Thank you.

Best regards,

Marta






here is a work around.

ki=1;
kp=1.5;
w=314.159;

num=([kp ki kp*w.^2]);
den=([1 0 w.^2]);
sis=tf(num,den);


[RLDATA, ki] = rlocus (sis, 0.1, 0, 500);
%plot(rlocus(sis),"*","markersize",1)
rlocus(sis)

nr=roots(num);
dr=roots(den);
hold on 
plot(nr,"co","markersize",15)
plot(dr,"rx","markersize",15)
hold off



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Re: Help with rlocus appearance of initial location of poles and zeros

Beginner1
Hi Doug,

Thank you for your answer. The markersize for the origin of poles in root
locus is a good one since the "X" symbol is perfectly seen. However, the
location of zeros is not that observable. Still they are very small when I
execute this code:

%ki=1;

kp=1.5;

w=314.159;


num=([kp ki kp*w.^2]);

den=([1 0 w.^2]);

sis=tf(num,den);

[RLDATA, ki] = rlocus (sis, 0.1, 0, 500);

%plot(rlocus(sis),"*","markersize",1)

rlocus(sis)


nr=roots(num);

dr=roots(den);

hold on

plot(nr,"co","markersize",15)

plot(dr,"rx","markersize",15)


hold off


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

I tried to increase the markersize but I didn´t observe any improvement.

Best regards,

Marta



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Re: Help with rlocus appearance of initial location of poles and zeros

Beginner1
In fact, what is happening is the dispersión of the "O" marker for zero
locations as soon as the poles trajectories converge at the real axis:

Kp=1.5, Ki=940
 
<http://octave.1599824.n4.nabble.com/file/t372684/1st.jpg>


Kp=1.5, Ki=960

<http://octave.1599824.n4.nabble.com/file/t372684/2nd.jpg>

when changing the value of Ki from 940 to 960 in this code:

/ pkg control load

ki=960;

kp=1.5;

w=314.159;


num=([kp ki kp*w.^2]);

den=([1 0 w.^2]);

sis=tf(num,den);

%[RLDATA, ki] = rlocus (sis, 1, 0, 40);

%plot(rlocus(sis),"*","markersize",1)

rlocus(sis)


nr=roots(num);

dr=roots(den);

hold on

plot(nr,"co","markersize",15)

plot(dr,"rx","markersize",15)


hold off/

So can anybody give me advice on how to avoid this movement of the zero
marker?

Thank you






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Re: Help with rlocus appearance of initial location of poles and zeros

Doug Stewart-4


On Tue, Jan 30, 2018 at 5:18 AM, Beginner1 <[hidden email]> wrote:
In fact, what is happening is the dispersión of the "O" marker for zero
locations as soon as the poles trajectories converge at the real axis:

Kp=1.5, Ki=940

<http://octave.1599824.n4.nabble.com/file/t372684/1st.jpg>


Kp=1.5, Ki=960

<http://octave.1599824.n4.nabble.com/file/t372684/2nd.jpg>

when changing the value of Ki from 940 to 960 in this code:

/ pkg control load

ki=960;

kp=1.5;

w=314.159;


num=([kp ki kp*w.^2]);

den=([1 0 w.^2]);

sis=tf(num,den);

%[RLDATA, ki] = rlocus (sis, 1, 0, 40);

%plot(rlocus(sis),"*","markersize",1)

rlocus(sis)


nr=roots(num);

dr=roots(den);

hold on

plot(nr,"co","markersize",15)

plot(dr,"rx","markersize",15)

Change to plot commands to


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

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


 

hold off/

So can anybody give me advice on how to avoid this movement of the zero
marker?

Thank you






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Re: Help with rlocus appearance of initial location of poles and zeros

Beginner1
Thank you a lot. This definitely solves the issue.

Best regards



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