Re: fit a complex function

*To*: mathgroup at smc.vnet.net*Subject*: [mg98975] Re: fit a complex function*From*: dh <dh at metrohm.com>*Date*: Thu, 23 Apr 2009 06:41:34 -0400 (EDT)*References*: <gsmn0k$d2r$1@smc.vnet.net>

Hi, 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] ==================================== Daniel 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? > >