"Warning: Imaginary parts of complex X and/or Y arguments ignored" in fminserach and optimtool
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Dear all,
I am trying to fit a curve to experimental data by use of "optimtool" and "fminsearch".
But I receive a warning which says " Imaginary parts of complex X and/or Y arguments ignored". I have this warning from the first iteration.
Any idea to solve this warning is appreciated. Thanks in advance Best regards Victor
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Accepted Answer
Walter Roberson
on 5 Mar 2012
If your fitting inherently involves imaginary quantities, then please note:
fminsearch only minimizes over the real numbers, that is, x must only consist of real numbers and f(x) must only return real numbers. When x has complex variables, they must be split into real and imaginary parts.
2 Comments
Walter Roberson
on 5 Mar 2012
Beware of log vs log10
See also
http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
More Answers (1)
Sean de Wolski
on 5 Mar 2012
Evaluate your function at the initial values you provide. Is the result complex? If so, that's the reason for the warning. We can't be of much more assistance without seeing reproduction steps.
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