[R] Help on optim

[Ben Bolker]

Dimitris Rizopoulos <dimitris.rizopoulos <at> med.kuleuven.be> writes:

> 
> you don't need L-BFGS-B in this case since you can easily 
> re-parameterize you problem, i.e., you can always write:
> 
> pi_i = exp(a_i) / sum(exp(a_i)), with e.g., a_1 = 0
> 
> and thus maximize with respect to a_i's.
> 
> I hope it helps.
> 
> Best,
> Dimitris

  although this may be problematic if some
of the original parameters lie on the boundary ...