[R] lme convergence

[Spencer Graves]

	  Does anyone know how to obtain the 'returnObject' from an 'lme' run 
that fails to converge?  An argument of this name is described on the 
'lmeControl' help page as, "a logical value indicating whether the 
fitted object should be returned when the maximum number of iterations 
is reached without convergence of the algorithm. Default is 'FALSE'."

	  Unfortunately, I've so far been unable to get it to work, as 
witnessed by the following modification of an example from the '?lme' 
help page:

 > library(nlme)
 > fm1 <- lme(distance ~ age, data = Orthodont,
+            control=lmeControl(msMaxIter=1))
Error in lme.formula(distance ~ age, data = Orthodont, control = 
lmeControl(msMaxIter = 1)) :
	iteration limit reached without convergence (9)
 > fm1
Error: object "fm1" not found
 > fm1 <- lme(distance ~ age, data = Orthodont,
+            control=lmeControl(msMaxIter=1,
+              returnObject=TRUE))
Error in lme.formula(distance ~ age, data = Orthodont, control = 
lmeControl(msMaxIter = 1,  :
	iteration limit reached without convergence (9)
 > fm1
Error: object "fm1" not found	

	  I might be able to fix the problem myself, working through the 'lme' 
code line by line, e.g., using 'debug'.  However, I'm not ready to do 
that just now.

	  Best Wishes,
	  Spencer Graves

Ravi Varadhan wrote:
> Use "try" to capture error messages without breaking the loop.
> ?try
> 
> --------------------------------------------------------------------------
> Ravi Varadhan, Ph.D.
> Assistant Professor,  The Center on Aging and Health
> Division of Geriatric Medicine and Gerontology
> Johns Hopkins University
> Ph: (410) 502-2619
> Fax: (410) 614-9625
> Email:  rvaradhan at jhmi.edu
> Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html 
> --------------------------------------------------------------------------
> 
>> -----Original Message-----
>> From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-
>> bounces at stat.math.ethz.ch] On Behalf Of Pryseley Assam
>> Sent: Wednesday, June 28, 2006 12:18 PM
>> To: R-Users
>> Subject: [R] lme convergence
>>
>> Dear R-Users,
>>
>>   Is it possible to get the covariance matrix from an lme model that did
>> not converge ?
>>
>>   I am doing a simulation which entails fitting linear mixed models, using
>> a "for loop".
>>   Within each loop, i generate a new data set and analyze it using a mixed
>> model.  The loop stops When the "lme function" does not converge for a
>> simulated dataset. I want to inquire if there is a method to suppress the
>> error message from the lme function, or better still, a way of going about
>> this issue of the loop ending once the lme function does not converge.
>>
>>   Thanks in advance,
>>   Pryseley
>>
>>
>> ---------------------------------
>>
>>
>> 	[[alternative HTML version deleted]]
>>
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