Your example is not self-contained, which makes it more difficult 
to answer your question. 
      However, I believe you should be able to answer the question by 
studying the examples on the help pages for "gnls" and possibly 
"corCompSymm", using the following additional commands: 
# To see a list of functions you can apply to objects of class "gnls":
methods(class='gnls')
# With luck, one of these will contain the answer to your question.
# To see the "structure" of the "res" object returned by
"gnls".
str(res)
      If these hints are not adequate, please provide a minimal, 
self-contained example, as requested in the posting guide 
"www.R-project.org/posting-guide.html".  You should be able to
construct
such fairly easily by modifying one of the examples in the "gnls" and 
"corCompSymm" help pages. 
      Hope this helps.
      Spencer Graves
Mahbub Latif wrote:> Hello list:
>
> How to extract the value of "Rho" from a gnls() object. I am
using gnls()
> function similar to
>
> res <- gnls(y~SSmicmen(),correlation=corCompSymm(form~1|b),data=dat)
>
> Thanks in advance,
>
> Mahbub.
>
>