Error when using step-command

9 次查看（过去 30 天）
Marcus Carlsson
Marcus Carlsson 2020-9-25
评论： Star Strider 2020-9-25
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
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

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Star Strider
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
显示 1更早的评论
Marcus Carlsson
Marcus Carlsson 2020-9-25
Hi!
You were right, thank you very much!

请先登录，再进行评论。

更多回答（1 个）

Fangjun Jiang
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

类别

在 Help Center 和 File Exchange 中查找有关 MATLAB 的更多信息

标签

产品


版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by