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MathGroup Archive 1998

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Re: NonLinearRegress question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg12923] Re: [mg12860] NonLinearRegress question
  • From: "Jrgen Tischer" <jtischer at col2.telecom.com.co>
  • Date: Wed, 24 Jun 1998 03:44:43 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

Oh Easan,
if you just correct the bugs: fun vs. func and t vs. z.

Jrgen

-----Original Message-----
From: Easan Siviniah <easan at mrl.ucsb.edu> To: mathgroup at smc.vnet.net
Subject: [mg12923] [mg12860] NonLinearRegress question


>Hi folks,
>
>I'm writing some data fitting code on Mathematica that uses the add-on
>package
>'NonLinearRegress'. However I'm currently stumped because the model I
>use
>for fitting involves the use of conditional 'Ifs'. It seems that
>Mathematica does not recoginise such a function as numerical.
>Does Anyone have an idea of how to get round this. I've included a
>typical
>but simplified example below.
>
>In[1]      Clear[fun,t,x,y]
>              fun[t_,x_,y_]:=If[t<10,t^2 x + Log[t] y, t^3 x + Log[t] =
y]
>
>              data=Table[{t,N[fun[t,2,3]]},{t,1,21,2}] Out[1]
>{{1,2.},{3,21.2958},{5,54.8283},{7,103.838},{9,168.592},{11,2669.19},{13
,
>
>    4401.69},{15,6758.12},{17,9834.5},{19,13726.8},{21,18531.1}}
>
>In[2]       << Statistics`NonlinearFit`
>                NonlinearRegress[data,
>                N[func[t,a,b]] ,z, {{a,{-100,-101}},{b,{2,3}}},
>                RegressionReport -> BestFitParameters,
>                 Method->FindMinimum,
>                ShowProgress -> True]
>
>Out[2]  NonlinearRegress::"nonnum": "The model is not numerical at
>(******)
>             Check that all model parameters are included in the
>parameter list.
>
>



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