[R] implementing user defined covariance matirx

[Jonathan Smith]

I am trying to implement my own covariance matrix into R.    Then be able to 
use it in gls or lme or nlme to analyze some data.  I simply want to use 
corr=mymodel(form ~tim/peep) same as can use corr= corAR1 and many others.   
Having a terrible time trying to figure out how to do this.   I have found 
documentation saying that you can do this but cant find out how.  Any 
suggestings would be greatly  appreciated.

My covariance matrix is:

| 1	s1^g  	s2^g 	s3^g	… |
| s1^g	 1	s1^g	s2^g	… |
| s2^g	s1^g	 1	s1^g    ... |
| s3^g	s2^g	s1^g	1 	… |
|  :	   :	        :	:	: :: |
|  :	   :	       :	:	:::: |


Thankyou kindly for your time
Jonathan Smith