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
Hi, 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 a,b,c,d>]^2 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 result. 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? Thanks! Sebastian (For those interested: I am trying to calculate the complex refractive index of a thin film from reflectance measurements as a function of angle) Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.