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

        Michel Berkelaar
        michel@es.ele.tue.nl

whose source was

        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
(/netlib/ampl/solvers/lpsolve/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.  Sample makefiles makefile4.u and
makefile4.vc are for LP_SOLVE 4.0 under Linux and MS Windows.

More recently, source for an updated LP_SOLVE (e.g., version 5.5.2)
can be found at http://sourceforge.net/projects/lpsolve/ .
Sample makefiles makefile.u (for Linux) and makefile.vc (for MS Windows)
are for LP_SOLVE 5.5.2.

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).