Solver lbfgsb minimizes functions subject only to simple-bound
constraints.  It is based on L-BFGS-B, by Ciyou Zhu, Richard Byrd,
Peihuang Lu, and Jorge Nocedal; see

	http://www.ece.nwu.edu/~nocedal/software.html

for pointers to more information on the limited-memory BFGS algorithm
implemented in L-BFGS-B.  Relevant papers include

	%A Ciyou Zhu
	%A Richard H. Byrd
	%A Peihuang Lu
	%A Jorge Nocedal
	%T Algorithm 778: L-BFGS-B: Fortran Subroutines for
	Large-Scale Bound-Constrained
	Optimization
	%J ACM Trans. Math. Software
	%V 23
	%N 4
	%D 1997
	%P 550-560
	
	%A Richard H. Byrd
	%A Peihuang Lu
	%A Jorge Nocedal
	%A Ciyou Zhu
	%T A Limited Memory Algorithm for Bound Constrained Optimization
	%J SIAM J. Sci. Comput.
	%V 16
	%N 5
	%D 1995
	%P 1190-1208


Source file routines.f comes from

	ftp://ftp.mcs.anl.gov/pub/neos/Lbfgs/Lbfgsb.2.1.tar.gz

Execute

	lbfgsb -?

for a summary of usage and

	lbfgsb -=

to see keywords that may appear in assignments in $lbfgsb_options
or the lbfgsb command line.

Possible solve_result_num values for lbfgsb:

000	Solved: maxnorm(projected gradient) <= pgtol.
100	Solved? relative function change <= macheps * factr.
101	No objective: nprob was out of range of stub.nl had no objectives.
400	More than maxfun function and gradient evaluations.
401	More than maxit iterations.
500	Probable bug: inconsistency in linesearch routine.
501	Error -- probably a bug.