I've found the problem, but someone who knows more about nls() will have
to fix it.
The problem is that in the demo code below, n1 ends up being an nls
object, but n1$call$control is NULL. profiler.nls() assumed that the
nls object passed to it has a non-NULL element there, and doesn't check.
I've fixed the code so now it doesn't crash, but it now dies with this
error instead:
> confint(n1) ## boom
Waiting for profiling to be done...
Error in prof$getProfile() : 'control$maxiter' absent
I'll commmit my change to R-devel and R-patched shortly.
Duncan Murdoch
On 12/22/2005 1:23 PM, [EMAIL PROTECTED] wrote:
> Full_Name: Ben Bolker
> Version: 2.2.1
> OS: Windows XP and 2000
> Submission from: (NULL) (128.227.60.124)
>
>
> The following code, using confint() to try
> to get confidence intervals on an nls object
> that has been fitted with algorithm="port"
> reliably crashes R 2.2.0 and 2.2.1 with the
> latest version of MASS on a Windows 2000 and
> a Windows XP machine here. I *think* earlier
> versions of MASS may not have crashed, but
> I have now updated the versions on most of
> my machines and don't have a test version handy.
>
> On XP, I get an error-report-do-you-want-
> to-send-this-to-Microsoft dialog box. On 2000
> I get a "Rgui has generated errors ..." dialog box.
>
> I can get this far:
>
> debug: profiledModel <- .Call("nls_iter", fittedModel, ctrl, trace,
> PACKAGE = "stats")
>
> Browse[1]> where
> where 1: prof$getProfile()
> where 2: profile.nls(object, which = parm, alphamax = (1 - level)/4)
> where 3: profile(object, which = parm, alphamax = (1 - level)/4)
> where 4: confint.nls(n1)
> where 5: confint(n1)
>
> I'm not set up to debug compiled code on Windows, and I haven't
> been able to reproduce the problem on Linux.
>
> set.seed(1001)
> x = runif(200)
> a =1
> b = 1
> c = -0.1
> y = a+b*x+c*x^2+rnorm(200,sd=0.05)
> plot(x,y)
> curve(a+b*x+c*x^2,add=TRUE)
> n1 = nls(y~a+b*x+c*I(x^2),start=c(a=1,b=1,c=0.1),algorithm="port")
> confint(n1) ## boom
>
> N.B.: It only crashes if algorithm="port" is specified.
>
> ## [1] "Windows 2000 Professional (build 2195) Service Pack 4.0"
> ##
> ## > R.version
> ## _
> ## platform i386-pc-mingw32
> ## arch i386
> ## os mingw32
> ## system i386, mingw32
> ## status
> ## major 2
> ## minor 2.0
> ## year 2005
> ## month 10
> ## day 06
> ## svn rev 35749
> ## language R
> ##
> ## MASS
> ##
> ## Version: 7.2-23
> ## Date: 2005-12-08
> ##
> ##
>
> ## "Windows XP Professional (build 2600) Service Pack 2.0"
> ## _
> ##platform i386-pc-mingw32
> ##arch i386
> ##os mingw32
> ##system i386, mingw32
> ##status
> ##major 2
> ##minor 2.0
> ##year 2005
> ##month 10
> ##day 06
> ##svn rev 35749
> ##language R
>
> ##
> ##Version: 7.2-23
> ##Date: 2005-12-08 ## CRASH
>
> ##> R.version
> ## _
> ##platform i386-pc-mingw32
> ##arch i386
> ##os mingw32
> ##system i386, mingw32
> ##status
> ##major 2
> ##minor 2.1
> ##year 2005
> ##month 12
> ##day 20
> ##svn rev 36812
> ##language R
> ## CRASH
>
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