Re: appearance of rlocus

[Rik]

On 01/29/2018 09:00 AM, address@hidden wrote:

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

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01/29/2018 02:51 AM

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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

Marta,

This is more of a topic for the help list than the maintainer's list.  Perhaps you could move the conversation with Doug over to that list. Also, there must be some misunderstanding about what code you are running.  The sample above doesn't even pass the interpreter without errors.  The variable 'ki' is commented out at the beginning of the code so when the line

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

is executed 'ki' is undefined and Octave just stops for me.

I just uncommented that first line and I get a very different result, but the zeros are clearly visible.

--Rik