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).