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. > >