Error while using transfer function 'tf'
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I tried different inputs as numerator and denominator to create a transfer function using 'tf' command, but my MATLAB leaves this message everytime: 'Incorrect number or types of inputs or outputs for function 'tf''. And this exact code runs perfectly in online MATLAB FYI. Any help is appreciated!
theta_hat = [-1.77627176214971;0.790085804375558;-0.0407175636083817;0.0479175052321617];
a1 = theta_hat(1); a2 = theta_hat(2); b0 = theta_hat(3); b1=theta_hat(4);
num=[b0 b1];den=[1 a1 a2];gz = tf(num,den);
采纳的回答
Please check if you have a user-defined function m-file with the same name as 'tf' that is saved in the current path.
which -all tf
13 个评论
Keerthik Dhivya
2023-11-18
Please find the attached result i have got in command window here:
Sam Chak
2023-11-18
Thanks @Keerthik Dhivya, I see it now. It appears that the Control System Toolbox is not installed. The 'tf' function from the Control System Toolbox is necessary to represent linear dynamical systems in transfer function form. This likely explains why it returns the error message 'Incorrect number or types of inputs or outputs for function tf'.
Keerthik Dhivya
2023-11-18
You're welcome, @Keerthik Dhivya. Feel free to post a new question if you encounter the control design problem. The plant gz(s) is unstable.
theta_hat = [-1.77627176214971;0.790085804375558;-0.0407175636083817;0.0479175052321617];
a1 = theta_hat(1); a2 = theta_hat(2); b0 = theta_hat(3); b1=theta_hat(4);
num=[b0 b1]; den=[1 a1 a2]; gz = tf(num,den)
step(gz)
Keerthik Dhivya
2023-11-18
joseph timoney
2023-12-7
Hi, did you find an answer to this. I have the exact same problem. It just won't work in the desktop version and I don't have any other m-files withe the same name, Thanks, Joe
Walter Roberson
2023-12-7
What code are you executing, and what error message are you getting?
Do you have the Control System Toolbox installed and licensed?
Sam Chak
2023-12-7
@joseph timoney, please type this and report what you see on the status output and the errmsg output:
[status, errmsg] = license('checkout', 'Control_Toolbox')
joseph timoney
2023-12-7
Hi Sam it says
[status, errmsg] = license('checkout', 'Control_Toolbox')
status =
1
errmsg =
0×0 empty char array
I have a sitewide license with my institution. Let me know what you think, thanks,
Sam Chak
2023-12-7
If you get exactly the same error message, "Incorrect number or types of inputs or outputs for function 'tf'", can you show the full code so that we can test it out?
joseph timoney
2023-12-7
numerator = 1;
denominator = [2,3,4];
sys = tf(numerator,denominator)
"Incorrect number or types of inputs or outputs for function 'tf'."
Is there a conflict beteen tf in the signal processing toolbox and tf in the control toolbox?
Dyuman Joshi
2023-12-7
编辑：Dyuman Joshi
2023-12-7
That code checks whether a particular item is licensed or not.
Type "ver" in the command window and see if the Control System Toolbox is installed or not.
@joseph timoney, If the Control System Toolbox is installed in your machine, you should see the tf.m file under the control folder. Also use ver as advised by @Dyuman Joshi.
ver
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