>>>>> "DB" == Douglas Bates <[EMAIL PROTECTED]>
>>>>> on Wed, 7 Feb 2007 17:24:40 -0600 writes:
DB> On 2/7/07, This Wiederkehr <[EMAIL PROTECTED]> wrote:
>> I tried to fit data with the following function:
>>
>> fit<-nls(y~ Is*(1-exp(-l*x))+Iph,start=list(Is=-2e-5,l=2.3,Iph=-0.3
>> ),control=list(maxiter=500,minFactor=1/10000,tol=10e-05),trace=TRUE)
>> But I get only a singular Gradient warning...
DB> Did you get any trace output at all? It is not clear if you got the
DB> singular gradient warning before the first iteration completed, which
DB> means there is a problem at the starting estimates, or after a few
DB> iterations. Without the data it is difficult to decide.
>> the data can by found attached(there are two sampels of data col 1/2 and
>> 3/4).
DB> Thanks for offering to include the data. My copy of your message did
DB> not have the data enclosed. Did you perhaps forget to attach the
DB> file?
More probably he did not attach them with mime type "text/plain".
Many e-mail clients nowadays attach everything and notably text
as unspecified binary ("application/octet-stream").
For security (and anti-spam) reasons, such attachments are
eliminated from postings.
I've now slightly modified this content-filtering option for
R-help, such that (I think) such e-mails will be *rejected* instead
of just the attachment removed -- I'm just trying that now,
attaching a 2 line text file
Martin
>> I tried to fix it by chanching the start parameters but that didn't solve
>> the problem.
>> Would it be a possibiliti to use the selfstart Model? How?
DB> Yes. Try SSasymp. I believe that model is equivalent to your model
DB> but in a different parameterization.
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