Re: inability to pass argument(s) to functions..

*To*: mathgroup at smc.vnet.net*Subject*: [mg29891] Re: [mg29878] inability to pass argument(s) to functions..*From*: "Mark Harder" <harderm at ucs.orst.edu>*Date*: Tue, 17 Jul 2001 01:00:36 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

All, A little editing: Some formatting glitch displaced the 2 lines in the input here-- In[405]:= aN={aN1,aN2}; {c,i,aN} Out[405]:= {c, i, {aN1, aN2}} -- and made the output look like some sort of crazy exponential. -mark -----Original Message----- From: Mark Harder <harderm at ucs.orst.edu> To: mathgroup at smc.vnet.net Subject: [mg29891] [mg29878] inability to pass argument(s) to functions.. > > Just to set the stage, I am trying to use NonlinearRegression >(again, alas) to fit a model with shared parameters to 2 sets of data, >which are distinguished from each other by an integer index which >appears in the data list in the NLR arguments as an extra independent >variable, which will be passed to the model function in the usual >fashion. This simple scheme fails, although I have tried several >alternative formulations of the model function because, apparently, NLR >is unable to pass the integer index into the model function. I have >enclosed a trial function which reproduces this behavior. I hope >someone can show me what I am doing "wrong" and how I can fix my >problem: > >(* definition of function *) > >In[478]:= >Clear[trialfn, i, ii, c, cc]; >trialfn[aN_List, c, i] := (Print[i]; >Return[c*aN\[LeftDoubleBracket]i\[RightDoubleBracket]] ) > >(* aN is a list *) > >In[405]:= {aN1,aN2}; > > {c, i, aN} >Out[405]= {c, i, {aN1, aN2}} > >(* pass numeric values explicitly *) > >In[482]:= >trialfn[{-3.4, -4.}, 0., 1 ] >Out[482]= >trialfn[{-3.4, -4.}, 0., 1] (* Doesn't understand command *) > > > >(* passed by replacement ( I think this is how NLR does it) *) > >In[487]:= >trialfn[aN, c, i ] /. {aN1 -> -3.4`, aN2 -> -4.`, c -> 1.`, i -> 2`} >an integer nor a list \ >of integers." >Out[487]= -4. (* correct evaluation, for i=2!! *) > >note the result of printing out the value of i, although the function >*is* evaluated. This doesn't work in NLR, however: > >fitData2 = {{0, 1, -3.320248485`}, {1, 1, -3.215648485`}, {2, > 1, -3.375939394`}, {0, 2, -4.312424242`}, {1, 2, -3.985844444`}, >{2, > 2, -4.300822222`}}; (* trial data for fitting *) > >In[476]:= best3D = NonlinearRegress[fitData2, trialfn[aN, c, i ] >, > {c, i}, { {aN1, {-3.4, -3.}}, {aN2, {-4., -3.}} }, > Method -> Gradient, Compiled -> False] > > >an integer nor a list \ > of integers. > > "From In[476]:= >FindMinimum::"fmgs": "Could not symbolically find the gradient of >\!\(#1\\ \(\ >\(\(\({aN1, aN2}\)\) \[LeftDoubleBracket] #2 >\[RightDoubleBracket]\)\)\). Try \ >using the default method, giving two starting values for each variable." > >.... and a long list of repeating error messages ending with the >unevaluated output. > >Thanks, > >mark e. harder > >