[R] nls: singular convergeance

[Redding, Matthew]

Hi Rolf and others

Will this make any difference to the convergence?

Thanks

Matt



Matt Redding, Ph.D.
Soil chemist/Geochemist
Principal Scientist
Agri-Science Queensland
Ph 0746 881372
Mob 0408 787100
Fax 07 46881192

----- Original Message -----
From: Rolf Turner <rolf.turner at xtra.co.nz>
To: Redding, Matthew
Cc: r-help at r-project.org <r-help at r-project.org>
Sent: Thu Oct 13 18:04:53 2011
Subject: Re: [R] nls: singular convergeance

On 13/10/11 18:02, Redding, Matthew wrote:
> Dear R-experts,
>
> I have 28 data points that I would like to fit with a non linear
> broken-stick -- with three fitted parameters.
> When I view trace -- and use the final values as lines on the graph of
> data -- it looks pretty good.
>
> Q1. Why am I getting singular convergeance?
> Q2. Can you suggest another approach that may prove more satisfying?
<SNIP>

Have you thought of using the "segmented" package instead
of rolling your own with nls?

     cheers,

         Rolf Turner

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