[Rd] Bug in numericDeriv (was: [R] nls confidence intervals) (PR#3746)

[dmurdoch at pair.com]

Moved from r-help:

On Thu, 14 Aug 2003 09:08:26 -0700, Spencer Graves
<spencer.graves at pdf.com> wrote :

>p.s.  The following command in S-Plus 6.1 seems to work fine but 
>produces an error in R 1.7.1:
>
>nls(y~a, data=tstDf, start=list(a=1))
>Error in nlsModel(formula, mf, start) : singular gradient matrix at 
>initial parameter estimates

This looks like a bug in numericDeriv, which finds a derivative of 0
rather than 1 for da/da.  I've cc'd the author.

Duncan