I'm trying to simplify an expression or equation symbolically and I get the same error every time. Undefined function or variable 'x'.

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I'm trying to simplify an expression symbolically and I get the same error every time.
Undefined function or variable 'x'.
I'm even using the actual example matlab provides. Trying to just simplify the expression sin(x)^2 + cos(x)^2 I get the error everytime. I'm brand new...what am I missing.

Accepted Answer

Meghana Dinesh
Meghana Dinesh on 6 Feb 2016
Edited: Meghana Dinesh on 6 Feb 2016
What exactly is your command? It seems like you haven't told MATLAB what the value of x is. First, initialize a value for x and the carry on.
x = 0.5;
sin(x)^2 + cos(x)^2;
  4 Comments
Walter Roberson
Walter Roberson on 6 Feb 2016
simplify() requires the Symbolic Toolbox, and it works on symbolic expressions.
syms x
simplify( sin(x)^2 + cos(x)^2 )

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More Answers (1)

Bala Abhirami
Bala Abhirami on 25 May 2021
Edited: Bala Abhirami on 25 May 2021
The function u[1]/(u[2]^0.5) shows the error "result of the function is undefined" in matlab simulink user defined function. What could be the reason?
  1 Comment
Walter Roberson
Walter Roberson on 25 May 2021
Simulink uses MATLAB indexing syntax, so you need () instead of []
u(1)/(u(2)^0.5)
You might be able to use
u(1)/sqrt(u(2))

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