Solver "lpsolve" is based on lp_solve, a simplex-based code for linear
and integer programming problems by

        Michel Berkelaar
        michel@es.ele.tue.nl

whose source is

        ftp://ftp.es.ele.tue.nl/pub/lp_solve/lp_solve.tar.gz

The version of this source file that was available on 26 Feb. 2003
is file lp_solve_4.0.tar.gz, which was released under the LGPL license
(as explained in its README and LGPL.txt files).  Some executable
"lpsolve" binaries built from this source appear in the system-dependent
subdirectories of /netlib/ampl/student/solvers.

The makefile assumes this has been unpacked in the current directory
(solvers/lpsolve), giving subdirectory lp_solve_4.0 (or, for later
versions, a similarly named subdirectory, in which case you will need
to adjust the "LPSOLVE =" line in the makefile accordingly).

For a summary of using solver "lpsolve", execute

        lpsolve '-?'

Lpsolve reads keywords and values from the environment (shell) variable
lpsolve_options (known in an AMPL session as option lpsolve_options) and
from the command line.  Execute

	lpsolve -=

for a summary of keywords that lpsolve recognizes.


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

        Value   Message

        0       optimal
        200     infeasible
        300     unbounded
        500     bug
        501     failure
        502     integer programming failure

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