[R] nls

[Petr Pikal]

Hi

Why do you want to change your variable values? It smells a rat to 
me.

If you just change your a,b,c values nls arrives to some finite 
result (e.g. c=1.5 or c=0.3) . BTW by what magic you obtained such 
precise and wrong estimates for a,b,c?

HTH
Petr





On 15 Aug 2006 at 5:54, Xiaodong Jin wrote:

Date sent:      	Tue, 15 Aug 2006 05:54:51 -0700 (PDT)
From:           	Xiaodong Jin <close2ceo at yahoo.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] nls

>   Is there anyway to change any y[i] value (i=2,...6) to make
>   following NLS workable? 
> 
>   x <- c(0,5,10,15,20,25,30)
>   y <- c(1.00000,0.82000,0.68000,0.64000,0.66667,0.68667,0.64000)
>   lm(1/y ~~ x) nls(1/y ~~ a+b*x^c,
>   start=list(a=1.16122,b=0.01565,c=1), trace=TRUE)
> 
>   #0.0920573 :  1.16122 0.01565 1.00000 
> #Error in numericDeriv(form[[3]], names(ind), env) : 
> #        Missing value or an infinity produced when evaluating the
> #        model
> 
> 
> ---------------------------------
> 
> 
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Petr Pikal
petr.pikal at precheza.cz