[Help-glpk] glpk 4.63 release information

[Andrew Makhorin]

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GLPK 4.63 Release Information
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Release date: July 25, 2017

GLPK (GNU Linear Programming Kit) is intended for solving large-scale
linear programming (LP), mixed integer linear programming (MIP), and
other related problems. It is a set of routines written in ANSI C89 and
organized as a callable library.

        In this release:

        A "smart" LP perturbation was implemented in the primal and
        dual simplex solvers. Now LP is perturbed only if it is
        necessary, and by default perturbation is not activated.
        The sum of primal infeasibilites that appears in the terminal
        output of the primal simplex solver (as "inf = ...") now
        corresponds to the original bounds of variables. This allows to
        see how much perturbed solution violates the original bounds.

        The long-step technique was implemented for phase I of the
        primal simplex solver. This feature can be enabled by
        specifying --flip option for glpsol or by specifying
        glp_smcp.r_test = GLP_RT_FLIP on api level. For many LP
        instances the long-step technique allows reducing the number
        of simplex iterations to 30-70%. Please note that unlike the
        dual simplex, where this technique can be used on both phase I
        and II, for the primal simplex it can be used only on phase I,
        where the sum of primal infeasibilities (which is a convex
        piecewise linear function) is minimized.

        An internal objective scaling was included in both primal and
        dual simplex solvers. For many LP/MIP instances this feature
        improves numerical stability (for the dual solver) and prevents
        cycling near the optimum (for the primal solver).

        The Posix version of glp_time (glpk/src/env/time.c) was changed
        to resolve time_t issue on msys2. Thanks to Rob Schroeder
        <address@hidden> for bug report.

        Three new example models in MathProg were added:
        life_goe.mod (Conway's Game of Life garden of eden checker);
        tiling.mod (Rectifiable polyomino tilings generator);
        toto.mod (Covering code generator).
        Thanks to Peter Naszvadi <address@hidden> for contribution.

See GLPK web page at <http://www.gnu.org/software/glpk/glpk.html>.

GLPK distribution can be ftp'ed from <ftp://ftp.gnu.org/gnu/glpk/> or
from some mirror ftp sites; see <http://www.gnu.org/order/ftp.html>.

MD5 check-sum is the following:

430ebc2c5f6701c1bde9c33b7f54bd89 *glpk-4.63.tar.gz

GLPK is also available as a Debian GNU/Linux package. See its web page
at <http://packages.debian.org/stable/math/glpk-utils>.

Precompiled GLPK binaries (lib, dll, exe) for 32- and 64-bit MS Windows
can be downloaded from <http://winglpk.sourceforge.net/>.
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