Thanks to Hadley, William and Duncan for suggestions. I'm currently implementing a solution that is close to that of William and Duncan (and learning more about environments in the process). I suspect the reference classes are possibly a more reliable long term solution. I'll plead laziness until I find the other approach won't work.
For anyone interested in these issues, over the next few weeks the outcome of my investigations and trials should be on the SVN repository of R-forge under Optimization and Solving Tools, https://r-forge.r-project.org/R/?group_id=395, in particular within the packages optfntools and optimx. However, it will be late April before things stabilize. John Nash ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
