MathGroup Archive 2009

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: complex function fitting?

  • To: mathgroup at
  • Subject: [mg98331] Re: complex function fitting?
  • From: "Ned Lieb" < at>
  • Date: Wed, 8 Apr 2009 02:44:13 -0400 (EDT)
  • References: <grcgjg$pml$> <>

Just a clarification of my original question: I'm referring to a specific
issue I'm having using the NonlinearModelFit function, which fits lists of
data-points to functions of a type specified by the user (for example, say I
knew that my data fit an exponential equation (it doesn't, by the way, this
is just an example) with x as an independent variable: NonLinearModelFit
could find the constant A in the equation A*e^x that would give the function
that most closely approximated my data). My list of data is complex-valued
(with non-zero imaginary components). Mathematica returned an error message
saying I could only use real numbers. I was wondering whether there was a
way to get around this.


-----Original Message-----
From: dh [mailto:dh at] 
Sent: Monday, April 06, 2009 6:48 AM
To: Ned Lieb
Subject: [mg98331] Re: complex function fitting?

Hi Ned,
Mathematica works by default with complex numbres. E.g. using "Fit":
d = Table[{x + I y, Exp[x + y I ]}, {x, 0, 1, .1}, {y, 0, 1, .1}];
d = Flatten[d, 1];
pol = Fit[d, {1, x, x^2}, x]
yc = pol /. x -> d[[All, 1]];
ListPlot[{Re[#], Im[#]} & /@  (yc - d[[All, 2]]), PlotRange -> All]

Ned Lieb wrote:
> Does anyone know how I could extend the domain of Mathematica's
> function-fitting functions so I can use complex-valued data?

  • Prev by Date: Re: Difficulties with Re
  • Next by Date: Re: Does FindFit really use Norm[] when NormFunction -> Norm?
  • Previous by thread: Re: complex function fitting?
  • Next by thread: Re: complex function fitting?