Solver npopt is a nonlinear solver based on NPOPT, a nonlinear solver
by Philip E. Gill, Walter Murray and Michael A. Saunders.  NPOPT is an
updated version of NPSOL and is available from Professor Gill
to people who have NPSOL; contact peg@optimal.ucsd.edu (Philip Gill)
to see about getting source for npopt.a, a library form of NPOPT.
NPSOL is available from

	Stanford Business Software
	2680 Bayshore Parkway, Suite 304
	Mountain View, CA 94043
	Phone:	+1-415-962-8719
	Fax:	+1-415-962-1869

It is most convenient to invoke npopt with AMPL's solve command:

	ampl: option solver npopt;
	ampl: solve;

but npopt can also be run separately, with invocation syntax

	npopt stub [-AMPL] [keywd=[value] ...]

in which stub comes from AMPL's write command.  For example,

	> ampl -obfoo foo.mod foo.dat
	> npopt foo

demonstrates running npopt separately; the ampl invocation
writes file foo.nl (stub = "foo"), which npopt reads.

Command-line arguments to npopt either have the form
	keywd=
or
	keywd=value
where keywd is one of the key words described below.  Alternatively,
you can invoke npopt the way AMPL's solve command does, i.e.,

	npopt stub -AMPL [keywd=value ...]

where stub was specified in

	ampl -obstub ...
or
	ampl -ogstub...

Such an invocation causes npopt to read from stub.nl and to write stub.sol.

-----------------
Controlling npopt
-----------------

Npopt reads keywords and values from the environment (shell) variable
npopt_options and from the command line.  Execute

	npopt -=

for a summary of keywords that are synonyms for NPSOL keyword phrases.
You can also give NPSOL keyword phrases if you change blanks within
them to underscores and follow them with an = (equals sign).

------------------
Sample Invocations
------------------

  If you're using AMPL, just say

	option solver npopt;
	solve;

  If you've executed, say,

	ampl -objunk junk.model junk.data

then you could say

	npopt junk itera=300 linesearch=1e-6

to force npopt to run for at most 300 iterations and use linesearch
tolerance 1e-6.  With the Bourne shell, either of the invocations

	npopt_options='iterations=300 linesearch=1e-6' npopt junk
or
	npopt_options='iterations=300 linesearch=1e-6'
	export npopt_options
	npopt junk

would have the same effect; within AMPL, specifying

	option npopt_options 'iterations=300 linesearch=1e-6', solver npopt;
	solve;

would also have this effect.


The makefile assumes that npopt.a is a library built from the NPOPT
source.

-----------------------
solve_result_num values
=======================

Here is a table of solve_result_num values that "npopt" can return
to an AMPL session, along with the text that appears in the associated
solve_message.

	Value	Message

	0	optimal solution
	100	first-order optimal but not converged
	200	linear constraints infeasible
	201	nonlinear constraints infeasible
	400	major iteration limit
	501	Bug: INFORM = 5
	502	stuck (INFORM = 6)
	503	Bug: bad objective or constraints (INFORM = 7)
	504	Bug: INFORM = 8
	505	Bug: invalid input parameter (INFORM = 9)
	506	unexpected INFORM value
	507	solution aborted

-----------------------

Questions about this stuff?  Contact dmg@ampl.com (David M. Gay).