error) ss2tf is not read

In this way, the ss2tf function is not read. Other computers can read the same code, but not mine. It has already been reinstalled for the third time and control system toolbox is also installed. What is the solution?

[Ameer Hamza]

Run the command

which ss2tf

and show the output.

[Ji Hoon Kong]

>> which ss2tf

C:\Program Files\MATLAB\R2020a\toolbox\shared\controllib\general\ss2tf.m

this is my matlab's output

[Ji Hoon Kong]

function [num, den] = ss2tf(varargin)
%SS2TF  State-space to transfer function conversion.

etc

%   Copyright 1984-2011 The MathWorks, Inc.

this is ss2tf.m file's content (or was, before the copyrighted code was deleted)

[Walter Roberson]

Please show the output of

license('test','control_toolbox')

[Ji Hoon Kong]

>> license('test','control_toolbox')

ans =

1

>>

[Walter Roberson]

Please copy and paste the complete error message (not just a picture of the error message; it is easier for us to have it as text, please.)

[Ji Hoon Kong]

Do you want picture's error message?? i cant understand your question.

[Walter Roberson]

Is that the complete error message?

You have posted a picture of the error message. I would like to get the characters of the error message so that I can use a translation service as I do not read Korean.

[Walter Roberson]

I suggest deleting the line and retyping it. you might have an invisible character

[Ji Hoon Kong]

yeah that is complete error message. 오류발생 mean error occurrence.

other computer's matlab can read that code, but my labtop's matlab cant read ss2tf

[Ameer Hamza]

Ji, can you just copy and paste the following line and run it in the command window without typing anything else with it?

[num, den] = ss2tf(a,b,c,d);

[Walter Roberson]

That error message would not be the one for the case that ss2tf was not found or for ss2tf having an error in its code. That error message can only mean that there is something wrong with the characters or syntax of the line. All other cases would have longer error messages.

[Ji Hoon Kong]

[num, den] = ss2tf(a,b,c,d);

output is

'a' is not unrecognized function or variable.

[Ji Hoon Kong]

my matlab code is

m1 = 1;
m2 = 1;
k = 1;
t = linspace(0,10,173);
a =[0 1 0 0; -1*k/m1 0 k/m1 0;0 0 0 1; k/m2 0 -1*k/m2 0];
b = [0;1/m1;0;0];
c = [0 0 1 0];
%output measurement is the only x2
d = 0;
[num, den] = ss2tf(a,b,c,d);
step(num,den) 

and output is

error occurance:  ^  (line 51)
The dimensions are incorrect and the matrix cannot be rounded. Verify that the matrix is square and the exponential value is scalar. To perform matrix power operations by element, '.Please use '^'.

error occurance: poly (line 2)
output=x^3+x^2+x+1;

error occurance: ss2tf (line 30)
den = poly(p);

error occurance: asdfg (line 10)
[num, den] = ss2tf(a,b,c,d);

Answer 1

[Ameer Hamza]

Ah!! You see. Posting the full error message made the problem clear. You have defined a function named 'poly'. MATLAB also has a function named poly. This confuses MATLAB. Change the name of your function to something else.

Type

which poly -all

it will give you a list of functions. One of those functions was created by you. Change its name to something else.

[Ji Hoon Kong]

Thank you for your help. At first, only ss2tf appeared to be an error without these errors, so I thought it was not the cause. I wish you good health.

[Ameer Hamza]

I am glad to be of gelp.