[Help-glpk] non-official updated version of glpk (4.63 pre-release)

[Andrew Makhorin]

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

Andrew Makhorin


> A "smart" LP perturbation was also implemented in the dual simplex
> solver. This feature is similar to the one implemented in the primal
> simplex solver (see below).
> 
> Andrew Makhorin
> 
> 
> On Sat, 2017-07-01 at 14:58 +0300, Andrew Makhorin wrote:
> > Please see an updated version of glpk here:
> > http://sourceforge.net/projects/noumenon/files/tmp/
> > (Note that this is *not* an official release.)
> > 
> > In this release:
> > 
> > 1. See http://lists.gnu.org/archive/html/help-glpk/2017-06/msg00032.html
> > 
> > 2. A "smart" LP perturbation was implemented in the primal simplex
> > solver. Now LP is perturbed only if it is necessary, and by default
> > perturbation is not activated.
> > 
> > 3. 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 LP
> > solution violates the original bounds.
> > 
> > 4. The Posix version of glp_time (see glpk/src/env/time.c) was changed
> > to resolve time_t issue on msys2. 
> > Thanks to Rob Schroeder <address@hidden> for bug report.
> > 
> > 
> > Andrew Makhorin
> > 
> > 
> > 
> > _______________________________________________
> > Help-glpk mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/help-glpk
> > 
> 
> 
> 
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