[Help-glpk] glpk 4.13 release information

2006-11-13 Thread Andrew Makhorin
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GLPK 4.13 -- Release Information


Release date: November 13, 2006

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 C and
organized as a callable library.

In this release:

A tentative implementation of the primal two-phase simplex method based
on exact (bignum) arithmetic was included in the package.

On API level it is available through the routine lpx_exact, which is
similar to the routine lpx_simplex.

In the solver glpsol it is available through two new command-line
options: --exact and --xcheck. If the '--exact' option is specified,
glpsol solves LP instance using the exact simplex method; in case of
MIP it is used to obtain optimal solution of LP relaxation. If the
- --xcheck option is specified, LP instance (or LP relaxation) is solved
using the standard (floating-point) simplex method, however, then
glpsol calls the exact simplex routine to make sure that the final LP
basis is exactly optimal, and if it is not, to perform some additional
simplex iterations in exact arithmetic.

GLPK has its own low-level routines implementing operations on integer
and rational numbers that makes it independent on other software
packages. However, to attain a much better performance it is highly
recommended to install (before configuring GLPK) the GNU Multiple
Precision Arithmetic Library (GMP); see http://www.swox.com/gmp/ .
Using GMP library is able to make computations significantly faster.

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:

d1e7142be353da423ee4662499813541 *glpk-4.13.tar.gz

GLPK is also available as a Debian GNU/Linux package. See its web page
at http://packages.debian.org/stable/math/glpk.html.
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Re: RES: [Help-glpk] glpk 4.13 release information

2006-11-13 Thread Andrew Makhorin
 I simply replaced the lpx_simplex routine to lpx_exact on my program
 but the system freezes, when it tried to resolve PL's. There is some
 setup to do, before?

Nothing to do before is needed. Lpx_exact is much slower than the
floating-point solver due to huge rational numbers which may appear
as intermediate results; this is the only reason why your system
freezes. Try to call lpx_exact after lpx_simplex; this obtains the
same answer.



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