[R] gnls warning message

[Pedro Mardones]

Dear R users;
I was trying to fit a nonlinear model using gnls (nlme version 3.1-80,
R 2.5.0, WinXP) and I got the following error and warning message:

Error in gnls(ht ~ a1 * hd * (1 - a2 * exp(-a3 * (dbh/dq2))), data = hdat,  :
        Step halving factor reduced below minimum in NLS step
In addition: Warning message:
$ operator is deprecated for atomic vectors, returning NULL in:
control$nlmStepMax

What is new for me is the warning message. It appears when I try to
specify different settings using the control statement.For example:

> hm02<-gnls(ht~a1*hd*(1-a2*exp(-a3*(dbh/dq2))),data=hdat,
+ start=c(a1=1.04,a2=1.38,a3=2.88),weights=varExp(),
+ control=c(minFactor=1/2048))

Any comment will be appreciate

Thanks
PM