Variable ... is undefined on some execution paths

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Smaghuli
Smaghuli on 17 Apr 2015
Commented: Ambe Harrison on 19 Jul 2022 at 12:56
hello guys!
I hope somebody can advise me with respect the next code, when I run it into embedded editor from simulink embedded block, I have the error that Variable 'mu1' is undefined on some execution paths.
function [u_F,mu12,mu32] = fcn(s,delta)
%#codegen
a = 0.5;
mu12 = 0;
mu32 = 0;
y = 0;
if s <= -a
mu1 = 1;
mu2 = 0;
mu3 = 0;
elseif -a < s && s <= 0
mu1 = -1/a*s;
mu2 = 1/a*(s+a);
mu3 = 0;
elseif s > 0 && a >= s
mu1 = 0;
mu2 = -1/a*(s-a);
mu3 = 1/a*s;
elseif s > a
mu1 = 0;
mu2 = 0;
mu3 = 1;
end
mu12 = mu1;
mu32 = mu3;
y = (mu1*(-delta)+mu2*0+mu3*delta)/(mu1+mu2+mu3);
u_F = y;

Accepted Answer

Ryan Livingston
Ryan Livingston on 27 Apr 2015
Edited: Ryan Livingston on 27 Apr 2015
As the error says, there is a possible execution path on which mu1 is not defined. In particular, if all of the conditions in your if and elseif statements are false, then mu1,mu2,mu3 will not be defined.
To resolve this define them to default values either before the if:
mu1 = 0; mu2 = 0; mu3 = 0;
if s<= -1 ...
or add an else branch:
elseif s > a
mu1 = 0;
mu2 = 0;
mu3 = 1;
else
mu1 = 0;
mu2 = 0;
mu3 = 0;
end
The documentation explains this error message in more detail.
  2 Comments
Ambe Harrison
Ambe Harrison on 19 Jul 2022 at 12:56
Thank you Ryan Livingston your comment was very useful. It just solved a similar problem i encoutered.
Kind regards.

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