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Re: fit a complex function

  • To: mathgroup at
  • Subject: [mg98975] Re: fit a complex function
  • From: dh <dh at>
  • Date: Thu, 23 Apr 2009 06:41:34 -0400 (EDT)
  • References: <gsmn0k$d2r$>


you can not directly fit a complex function. But you may defined an 

error function of the parameters, that returns a real number, specifying 

the error. If you then search the minimum of this function over the 

parameters, you have solved your problem.

here is a simplified version with 1 dim. where we fit Exp[I a x]:


d = Table[{x, Exp[2 I x]}, {x, 0, Pi, Pi/10}];

err[a_] := Total[Abs[ d[[All, 2]] - ( Exp[a I #] & /@ d[[All, 1]])]^2];

FindMinimum[err[a], a]



Magician wrote:

> I have  data in the following form


> xi  , Fi            (xi is real but Fi is complex)


> i want to determine a fit by using function


> F(x, a , b,c, d)=    a Exp(- x^2/b) + c Sin( d x)


> a, b, c and d are complex numbers to be determined so as to accurately

> represent the data.


> How to do this problem?



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