ugly weird expression to be passed to R??

Robert Dodier wrote:
> On Mon, Jul 28, 2008 at 4:47 PM, dlakelan <dlakelan at street-artists.org> wrote:
> 
>> Does anyone have a suggestion for how to clean up this expression in
>> maxima before outputting to fortran?
> 
> Try "optimize" which looks for common subexpressions.
> 
> By the way, since Maxima includes a numerical minimization algorithm
> (LBFGS) I think it is worth a try to see if you can do the whole problem
> in Maxima. If you can send me some example data I will give it a try.

Thanks to all who helped with my expression. It turned out that I had to 
tune my model, and wound up with some other ugly expressions, but the 
use of scanmap(factorsum,expr) was extremely helpful in simplifying things.

I did try using lbfgs to get the maximum likelihood estimates, and it 
did work, even with 800+ data points in the likelihood expression. If I 
work more on this problem, I may try doing a MCMC sampling method for 
getting a bayesian posterior sample from the coefficients. Has anyone 
done anything like that in maxima before?

Thanks,
Dan