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Why MATLAB gives me this warning?

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Volkan Yangin
Volkan Yangin on 22 Mar 2017
Answered: Ju DING on 3 May 2018
Check function or try again with a different starting value. Exiting fzero: aborting search for an interval containing a sign change because NaN or Inf function value encountered during search. (Function value at 2.96273e+152 is -Inf.)
MATLAB gives me this warning on command window, but it still does calculations corretly after this warning. Is this an error? I have seen this warning for first time.
Thanks
  1 Comment
Volkan Yangin
Volkan Yangin on 22 Mar 2017
OK, i obtained the problem. First value of the function runs with 0 starting value and it gives me the warning.

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Accepted Answer

Rik
Rik on 22 Mar 2017
You are trying to find a zero of a function. This means Matlab will look for an x-value where the sign changes. During this proces it encountered a -inf value, after which it broke off its search.
What you need to do is written in the warning message: either check if your function is indeed the function you ment (i.e. check for typos), or adjust the starting value. If you have the function y=x and you start looking a x=100 and only increasing x, you'll never find the crossing. Apparently something equivalent has happened here.
Your Matlab is not broken, it just did not find the result it was looking for.

More Answers (1)

Ju DING
Ju DING on 3 May 2018
well,I also encounter the same problem as you.Please check your function input, maybe there is an illegal input.

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