Nonlinear Fit with complex model
- To: mathgroup at smc.vnet.net
- Subject: [mg19605] Nonlinear Fit with complex model
- From: mtir at my-deja.com
- Date: Sat, 4 Sep 1999 21:09:13 -0400
- Sender: owner-wri-mathgroup at wolfram.com
I am trying to fit a data set of real values with
a model that involves complex numbers, i.e.
model[a,b,c,d]=Abs[<complex expression in
When I am using NonlinearRegress (or
NonlinearFit) Mathematica complains that "One or
more derivatives of the model with respect to
parameters did not evaluate" and does not return a
I suspect that the reason for this is that Abs,
Re, Im etc. are not evaluated if the argument
is an expression rather than a number.
Does anyone know a way round this?
(For those interested: I am trying to calculate
the complex refractive index of a thin film from
reflectance measurements as a function of angle)
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