OPTIMIZER contains experimental and development versions of R optimization packages, esp. unconstrained or box constrained problems and utilities for testing of functions, evaluating proposed solutions, and improved optimization interfaces.
The project summary page you can find here.
Packages for optimization and solution of nonlinear systems of equations could include
Packages for utils functions include
Timing experiments with R based on the problem of minimizing the Rayleigh Quotient are discussed in RQtimes.Rnw, with the output file uploaded as RQtimes.pdf
Various approaches to optimization problems where parameters are constrained to obey some form of summation to a constant are described in sumscale16.Rnw, with the output file uploaded as sumscale16.pdf
There was an attempt to build an evolving "handbook" or "cheatsheet" for nonlinear least squares computations for R, but this seems not to have gained traction. The source file is of type .Rnw and can be processed with the knitR tools. This is nlshb.Rnw, with the latest output file uploaded as nlshb.pdf