Nonlinear fit for a non-differentiable function
- To: mathgroup at smc.vnet.net
- Subject: [mg43119] Nonlinear fit for a non-differentiable function
- From: Ahmed Sayeed <Ahmed.Sayeed at Tu-Ilmenau.De>
- Date: Wed, 13 Aug 2003 07:49:51 -0400 (EDT)
- Reply-to: Ahmed Sayeed <Ahmed.Sayeed at Tu-Ilmenau.De>
- Sender: owner-wri-mathgroup at wolfram.com
Hello friends,
I have to carry out a nonlinear fit where the fit function is non-differentiable w.r.t. one or
more of the parameters, because I have to take the absolute value in the definition of the function.
For example, f[x_,a_,b_]:=a*Sin[Abs[b]*x], where a and b are fit parameters. NonlinearRegress
fails, giving the following message:
NonlinearRegress::"unevldr": "One or more derivatives of the model with \
respect to parameters did not evaluate."
I shall be grateful if someone could suggest a way around this problem.
Thanks
Sayeed
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