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

        http://groups.yahoo.com/group/lp_solve/

The version of this source file that was available on 20 Oct 2004
is file lp_solve_5.1_source.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 has a line "LPSOLVE =" that you may need to adjust.

Note that lpsolve.c is made in such a way that it can be used with historical
versions of lp_solve. Versions 3, 4 and 5 are supported.
The makefiles end with the version number. So for example to make lpsolve for
version 5 on Windows, use makefile.vc5. For version 3, you would use makefile.vc3

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.

With this version, a lot of new keywords are added to have the full potential
of lp_solve.

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
        100     suboptimal
        200     infeasible
        300     unbounded
        500     bug
        501     failure
        502     integer programming failure

Questions about this stuff?
Contact dmg@ampl.com (David M. Gay) or peno@mailme.org (Peter Notebaert)

Also see AMPL.htm for more information or the lp_solve reference guide.

18/10/04 version 5.1.0.5
- Implemented the starting base / warm start feature.
- Added new lpsolve option coldstart to disable a starting base / warm start.
- Made building the model faster by making use of the version 5 features.
- A constant term in the objective function is now handled as a constant term instead
  of adding an extra column to the model. Makes it a bit faster.
- Implemented the free row feature. Previously, the lpsolve driver didn't supported this.

11/11/04 version 5.1.0.6
- No changes in driver.