On Fri, Oct 2, 2009 at 7:23 PM, Peter Ehlers <ehl...@ucalgary.ca> wrote:
> Hello Rainer,
>
> I think that your problem is with trying to fit a logistic model to
> data that don't support that model. Removing the first two points
> from your data will work (but of course it may not represent reality).
> The logistic function does not exhibit the kind of minimum that
> your data suggest.
>
>
Hi Peter
partly - when I do as you suggest, it definitely works, but this does not
change the behavioyur, that the error message always says:
" step factor 0.000488281 reduced below 'minFactor' of 0.000976562"
and it does not change to whichever value I try to set minFactor.
So either I am misunderstanding what the control argument for nls is doing,
or there is a bug in nls or in the error message.
Rainer
> -Peter Ehlers
>
>
> Rainer M Krug wrote:
>
>> Hi
>>
>> I want to change a control parameter for an nls () as I am getting an
>> error
>> message "step factor 0.000488281 reduced below 'minFactor' of
>> 0.000976562".
>> Despite all tries, it seems that the control parameter of the nls, does
>> not
>> seem to get handed down to the function itself, or the error message is
>> using a different one.
>>
>> Below system info and an example highlighting the problem.
>>
>> Thanks,
>>
>> Rainer
>>
>>
>> version _
>>>
>> platform i486-pc-linux-gnu
>> arch i486
>> os linux-gnu
>> system i486, linux-gnu
>> status
>> major 2
>> minor 9.2
>> year 2009
>> month 08
>> day 24
>> svn rev 49384
>> language R
>> version.string R version 2.9.2 (2009-08-24)
>>
>> sessionInfo()
>>>
>> R version 2.9.2 (2009-08-24)
>> i486-pc-linux-gnu
>>
>> locale:
>>
>> LC_CTYPE=en_ZA.UTF-8;LC_NUMERIC=C;LC_TIME=en_ZA.UTF-8;LC_COLLATE=en_ZA.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_ZA.UTF-8;LC_PAPER=en_ZA.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_ZA.UTF-8;LC_IDENTIFICATION=C
>>
>> attached base packages:
>> [1] stats graphics grDevices utils datasets methods base
>>
>> other attached packages:
>> [1] R.utils_1.2.0 R.oo_1.5.0 R.methodsS3_1.0.3 maptools_0.7-26
>> [5] sp_0.9-44 foreign_0.8-37
>>
>> loaded via a namespace (and not attached):
>> [1] grid_2.9.2 lattice_0.17-25
>>
>>
>> #############################################
>>
>> EXAMPLE:
>>
>> dat <- data.frame(
>> x = 2006:2037,
>> y = c(143088, 140218, 137964,
>> 138313, 140005, 141483, 142365,
>> 144114, 145335, 146958, 148584,
>> 149398, 151074, 152241, 153919,
>> 155580, 157258, 158981, 160591,
>> 162126, 163743, 165213, 166695,
>> 168023, 169522, 170746, 172057,
>> 173287, 173977, 175232, 176308,
>> 177484)
>> )
>>
>> nls( y ~ SSlogis(x, Asym, xmid, scal), data = dat, trace=TRUE)
>>
>> (newMinFactor <- 1/(4*1024))
>> nls( y ~ SSlogis(x, Asym, xmid, scal), data = dat,
>> control=nls.control(minFactor=newMinFactor), trace=TRUE)
>> nls( y ~ SSlogis(x, Asym, xmid, scal), data = dat,
>> control=c(minFactor=newMinFactor), trace=TRUE)
>>
>>
>> (newMinFactor <- 4/1024)
>> nls( y ~ SSlogis(x, Asym, xmid, scal), data = dat,
>> control=nls.control(minFactor=newMinFactor), trace=TRUE)
>> nls( y ~ SSlogis(x, Asym, xmid, scal), data = dat,
>> control=c(minFactor=newMinFactor), trace=TRUE)
>>
>>
>>
>>
--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)
Centre of Excellence for Invasion Biology
Natural Sciences Building
Office Suite 2039
Stellenbosch University
Main Campus, Merriman Avenue
Stellenbosch
South Africa
Cell: +27 - (0)83 9479 042
Fax: +27 - (0)86 516 2782
Fax: +49 - (0)721 151 334 888
email: rai...@krugs.de
Skype: RMkrug
Google: r.m.k...@gmail.com
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