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How to check "Undefined function or variable..." error with a variable in Matlab program?

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Tuoi
Tuoi 2013-8-23
I have code as follows:
for i=1:3
M=Mtmp(i)+(Mtmp(i+1)-Mtmp(i))*(t-t(i))/(t(i+1)-t(i));
end
And, Mtmp(i) and t(i) are two arrays which are defined in previous code snippet.
I run that code and receive an error: Undefined function or variable 'M'
I think, in Matlab, we can use a variable that we do not have to declare one, why do I receive that error? Thanks.

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回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-8-23
I am sure the error does not concern those lines of code. Post the entire code, maybe there is another line where M is used at the right of your expression.
  2 个评论
Azzi Abdelmalek
Azzi Abdelmalek 2013-8-24
[Tuoi commented]
Hi Azzi, I try to display the value of M by disp() function, I put the command line:
disp(['M= ',num2str(M)]);
after the above code (my post 1#), and run it, it generate that error (at disp() function). I hope you help me. Thanks.
Azzi Abdelmalek
Azzi Abdelmalek 2013-8-24
If M is defined, your code is correct. For example:
M=[1 2 3]
disp(['M= ',num2str(M)]);
Check If M is defined by typing M in Matlab command Windows

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