Error when using step-command
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I want to plot the step response of a transfer function but when I use step() i get an error message. I have tried to paste example-code from the matlab help but I still get error.
This is the example code:
(https://se.mathworks.com/help/control/ref/lti.step.html#d122e120846)
sys = tf(4,[1 2 10]);
step(sys)
The message I get is:
"Unable to use a value of type tf as an index."
Anyone who knows what might be wrong?
1 个评论
Jon
2020-9-25
I can't reproduce the problem running R2020a Update 3. I get a nice step response plot with those same two commands.
I assume you have tried clearing the workspace first, or reopening MATLAB completely just to make sure that there isn't some other variable assignment confusing things, and then, just type those two lines of code
采纳的回答
Star Strider
2020-9-25
I strongly suspect that you have a variable named ‘step’.
Run this is a script or your Command Window:
which step -all
I suspect the first line will be:
step is a variable.
If so, rename the variable to something else that is relevant to the context.
3 个评论
Fangjun Jiang
2020-9-25
编辑：Fangjun Jiang
2020-9-25
make sense
>> step=1:12
step =
1 2 3 4 5 6 7 8 9 10 11 12
>> step(sys)
Unable to use a value of type tf as an index.
Marcus Carlsson
2020-9-25
Star Strider
2020-9-25
As always, my pleasure!
更多回答（1 个）
Fangjun Jiang
2020-9-25
tf() is supposed to define a Transfer Function. You might have a variable called "tf" or other function called "tf". Do the following and see what are the returns
tf
which -all tf
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