[R] nls problem with R

[Mike Marchywka]

> Date: Wed, 4 May 2011 07:07:44 -0700
> From: sterlesser at hotmail.com
> To: r-help at r-project.org
> Subject: Re: [R] nls problem with R
>
> Thanks Andrew.
> I am sorry for some typos that I omit some numbers of T2.
> Based on your suggestion,I think the problem is in the initial values.
> And I will read more theory about the non-linear regression.

there is unlikely to be any magic involved, unlike getting hotmail to work.
As a tool for understanding your data, you should have some idea
of the qualitiative properties of model and data and the error
function you use to reconcile the two. 

If you can post your full data set I may post an R example of somethings
to try. I was looking for an excuse to play with nls, I'm not expert here,
and curious to see what I can do with your example for critique by others.
If you want to fully automate this for N contnuous parameters, you
can take a shotgun approach but not sure it helps other htna to
find gross problems in model or data.
I actually wrote a loop to keep picking random parameter values
and calculate and SSE between predicted and real data. What you soon
find is that this is like trying to decode a good crypto algorithm
by guessing- you can do the math to see the problem LOL.







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