I am sorry,Andrew,I don't get you.
Please forgive my poor English.
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Thanks Mike.
Your suggestion is really helpful.I did with the your instruction , it
really works out.
What's more,can you use this package
http://cran.r-project.org/web/packages/minpack.lm/index.html
it use Levenberg-Marquardt algorithm.
Can this package do with four parameters?
Thanks again
--
Vi
> Date: Thu, 5 May 2011 01:20:33 -0700
> From: sterles...@hotmail.com
> To: r-help@r-project.org
> Subject: Re: [R] nls problem with R
>
> ID1 ID2 t V(t)
> 1 1 0 6.053078443
> 2 1 0.3403 5.56937391
> 3 1 0.4181 5.454844
Apologies, but I don't see a question here ... am I missing something
obvious?
Andrew
On Thu, May 05, 2011 at 01:20:33AM -0700, sterlesser wrote:
> ID1 ID2 t V(t)
> 1 1 0 6.053078443
> 2 1 0.3403 5.56937391
> 3 1 0.4181 5.45484486
>
ID1 ID2 t V(t)
1 1 0 6.053078443
2 1 0.3403 5.56937391
3 1 0.4181 5.45484486
4 1 0.4986 5.193124598
5 1 0.7451 4.31386722
6 1 1.0069 3.645422269
7 1 1.5535 3.587710965
8
the dataset's form is changed after my post
so I repost it here
t
0
0.3403
0.4181
0.4986
0.7451
1.0069
1.5535
1.8049
2.4979
6.4903
13.5049
27.5049
41.5049
V(t)
6.053078443
5.56937391
5.45484486
5.193124598
4.31386722
3.645422269
3.587710965
3.740362689
3.699837726
2.908485019
1.888179494
1.17609
> Date: Wed, 4 May 2011 07:07:44 -0700
> From: sterles...@hotmail.com
> To: r-help@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
-project.org] On
Behalf Of sterlesser
Sent: Wednesday, May 04, 2011 10:08 AM
To: r-help@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
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.
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Thanks Ruben.
Your suggestion about more deeper analysis about the model itself is really
helpful.
I am trying out some new initial values based on the analysis of the special
T2 in the model.
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-Mensaje original-
> De: r-help-boun...@r-project.org
> [mailto:r-help-boun...@r-project.org] En nombre de Andrew Robinson
> Enviado el: miércoles, 04 de mayo de 2011 9:15
> Para: sterlesser
> CC: r-help@r-project.org
> Asunto: Re: [R] nls problem with R
>
> The fac
The fact that T2 and V2 are of different lengths seems like a likely
culprit. Other than that, you need to find start points that do not
lead to a singular gradient. There are several books that provide
advice on obtaining initial parameter estimates for non-linear
models. Google Books might hel
the original data are
V2 =c(371000,285000 ,156000, 20600, 4420, 3870, 5500 )
T2=c( 0.3403 ,0.4181 ,0.4986 ,0.7451 ,1.0069 ,1.553)
nls2=nls(V2~v0*(1-epi+epi*exp(-cl*(T2-t0))),start=list(v0=10^7,epi=0.9,cl=6.2,t0=8.7))
after execution error occurs as below
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