Freely available optimization code

[Douglas Bates <bates@stat.wisc.edu>]

Does anyone know of high quality freely-available code for numerical
optimization?  I am part of the core group of developers for a
statistical programming environment called R (see the r-base Debian
package or http://cran.stat.wisc.edu).  For optimization we have been
using the Fortran code that supplements Dennis and Schnabel's book
"Numerical Methods for Unconstrained Optimization and Nonlinear
Equations".  When I compare it against some code from the Port
library, it doesn't perform as well.  I would like to replace it.

I would also much prefer to use C, C++ or Java but I do have two
constraints on code.  Since R is GPL'd we would need code with a
license that allowed us to use it in a GPL'd product.  Also, we tend
to store matrices as unidimensional arrays with the Fortran-style
column-major ordering.

I have looked at the SAL (Scientific Applications on Linux)
site but it would take a long time to search through such a catalog.
I am interested in whether someone knows of something off-hand.