How to change the step size of rlocus

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go_stone 2021-10-30

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https://ww2.mathworks.cn/matlabcentral/answers/1575213-how-to-change-the-step-size-of-rlocus

评论： go_stone 2021-10-31

Hi,everyone.I plot a locus with the function "rlocus",but the step size is a little long than I want. I want to change the default step size but I don't know how to do it. I would be appreciated if anyone can give me some advice,thank you all!

Below is the code

clear;
sys1=zpk([-1,0.25],[-2,0.5+0.5j,0.5-0.5j],1);
rlocus(sys1);

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Answer 1

Paul 2021-10-30

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https://ww2.mathworks.cn/matlabcentral/answers/1575213-how-to-change-the-step-size-of-rlocus#answer_820313

编辑：Paul 2021-10-30

在 MATLAB Online 中打开

rlocus() takes a second argument that defines the gains, k, where the points are plotted.

rlocus(sys,k)

Specify k to make the points on the locus as far apart or as close together as you want.

doc rlocus

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Paul 2021-10-31

编辑：Paul 2021-10-31

在 MATLAB Online 中打开

That second parameter, k, is a 1d-array of all the gain values that you want the root locus to cover. When you specify k as a single number, rlocus() plots just one point for each root. For example:

sys=tf(1,[1 5 1]);

k = 0:.1:10;

rlocus(sys,k)

Make the interval in k smaller to fill in the gap at the breakpoint

k = 0:.01:10;

rlocus(sys,k)

Values in k don't kneed to be equally spaced. So you can vary the spacing with k to get more or less closely spaced points on the locus in region of more or less interest.

k = [0:.1:3 3.01:.01:6 6.1:.1:10];

rlocus(sys,k)

Also, if you're going to post screen captures, please shrink them down by quite a bit. I have to scroll up/down and left/right by quite a bit and can't see the whole picture all at once.