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NEWS
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GLPK 4.60 (release date: Apr 01, 2016)
Some improvements were made in the primal and dual simplex
solvers to make the solution process more numerically stable.
An experimental long-step ratio test feature was added to the
dual simplex. On API level this feature is available thru the
GLP_RT_FLIP option. For glpsol it is available thru the options
--flip (for MIP) or --flip and --dual (for LP). This feature is
not documented yet.
Additional check was added to reject wrong solutions sometimes
reported by the PROXY heuristic.
A bug (memory leak) was fixed in the FPUMP heuristic routine.
Thanks to <[email protected]> for bug report.
The header sql.h was renamed to avoid conflicts with standard
ODBC headers. Thanks to Noli Sicad <[email protected]> for bug
report.
GLPK 4.59 (release date: Mar 11, 2016)
This is a maintainer release.
Some bugs were fixed and some improvements were made in the MIP
solver. Thanks to Chris Matrakidis <[email protected]> for bug
reports and patches.
The data file format used by API routines glp_read_graph and
glp_write_graph was changed. For more details please see the
document "GLPK: Graph and Network Routines" included in the
distribution.
Translation of the document "Modeling Language GNU MathProg"
to Brazilian Portuguese (pt-BR) was included (in LaTeX and pdf
formats). Thanks to Joao Flavio de Freitas Almeida
<[email protected]> for contribution.
GLPK 4.58 (release date: Feb 18, 2016)
The solution file format used by API routines glp_read_sol,
glp_write_sol, glp_read_ipt, glp_write_ipt, glp_read_mip, and
glp_write_mip was changed. For more details please see the GLPK
reference manual included in the distribution.
The tan function (trigonometric tangent) was added to
GNU MathProg modeling language. Thanks to Chris Matrakidis
<[email protected]> for contribution.
A new version of the document "Modeling Language GNU MathProg"
in Spanish was included (in LaTeX and pdf formats). Thanks to
Pablo Yapura <[email protected]> for contribution.
A check to determine if libtool needs '-no-undefined' flag to
build shared libraries on some platforms was added.
Thanks to Marco Atzeri <[email protected]> and Heinrich
Schuchardt <[email protected]> for suggestion.
A script to regenerate the configure script and the Makefiles
was added. Thanks to Heinrich Schuchardt <[email protected]>.
GLPK 4.57 (release date: Nov 08, 2015)
A new, more efficient implementation of the dual simplex method
was included in the package. This new implementation replaces
the old one, which was removed.
Option sr_heur was added to struct glp_iocp to enable/disable
the simple rounding heuristic used by the MIP solver. Thanks to
Chris Matrakidis <[email protected]> for suggestion.
New API routine glp_at_error was added and documented. Thanks
to Jeroen Demeyer <[email protected]> for suggestion.
Some minor typos were corrected in the GLPK documentation.
Thanks to Anton Voropaev <[email protected]> for typo
report.
An example application program TSPSOL was added. It uses the
GLPK MIP optimizer to solve the Symmetric Traveling Salesman
Problem and illustrates "lazy" constraints generation. For more
details please see glpk/examples/tsp/README.
GLPK 4.56 (release date: Oct 01, 2015)
A new, more efficient and more robust implementation of the
primal simplex method was included in the package. This new
implementation replaces the old one, which was removed.
A bug was fixed in a basis factorization routine. (The bug
appeared if the basis matrix was structurally singular having
duplicate row and/or column singletons.) Thanks to Martin Jacob
<[email protected]> for bug report.
Scripts to build GLPK with Microsoft Visual Studio 2015 were
added. Thanks to Xypron <[email protected]> for contribution
and testing.
GLPK 4.55 (release date: Aug 22, 2014)
Some internal (non-API) routines to estimate the condition of
the basis matrix were added. These routines are mainly intended
to be used by the simplex-based solvers.
Two open modes "a" and "ab" were added to GLPK I/O routines.
Thanks to Pedro P. Wong <[email protected]> for bug report.
Minor bug was fixed in the solver glpsol (command-line options
--btf, --cbg, and --cgr didn't work properly).
A serious bug was fixed in a basis factorization routine used
on the dense phase. (The bug might appear only if the number of
rows exceeded sqrt(2**31) ~= 46,340 and caused access violation
exception because of integer overflow.) Thanks to Mark Meketon
<[email protected]> for bug report.
Two API routines glp_alloc and glp_realloc were documented.
Thanks to Brian Gladman <[email protected]> for suggestion.
Translation of the document "Modeling Language GNU MathProg"
to Spanish was included (in LaTeX and pdf formats). Thanks to
Pablo Yapura <[email protected]> for contribution.
GLPK 4.54 (release date: Mar 28, 2014)
Block-triangular LU-factorization was implemented to be used
on computing an initial factorization of the basis matrix.
A new version of the Schur-complement-based factorization
module was included in the package. Now it can be used along
with plain as well as with block-triangular LU-factorization.
Currently the following flags can be used to specify the type
of the basis matrix factorization (glp_bfcp.type):
GLP_BF_LUF + GLP_BF_FT LUF, Forrest-Tomlin update (default)
GLP_BF_LUF + GLP_BF_BG LUF, Schur complement, Bartels-Golub
update
GLP_BF_LUF + GLP_BF_GR LUF, Schur complement, Givens rotation
update
GLP_BF_BTF + GLP_BF_BG BTF, Schur complement, Bartels-Golub
update
GLP_BF_BTF + GLP_BF_GR BTF, Schur complement, Givens rotation
update
In case of GLP_BF_FT the update is applied to matrix U, while
in cases of GLP_BF_BG and GLP_BF_GR the update is applied to
the Schur complement.
Corresponding new options --luf and --btf were added to glpsol.
For more details please see a new edition of the GLPK reference
manual included in the distribution.
A minor bug (in reporting the mip solution status) was fixed.
Thanks to Remy Roy <[email protected]> for bug report.
A call to "iodbc-config --cflags" was added in configure.ac
to correctly detect iodbc flags. Thanks to Sebastien Villemot
<[email protected]> for patch.
GLPK 4.53 (release date: Feb 13, 2014)
The API routine glp_read_mps was changed to remove free rows.
A bug was fixed in the API routine glp_read_lp. Thanks to
Gabriel Hackebeil <[email protected]> for bug report.
The zlib compression library used by some GLPK routines and
included in the package was downgraded from 1.2.7 to 1.2.5 (as
in GLPK 4.50) because of addressability bugs on some 64-bit
platforms. Thanks to Carlo Baldassi <[email protected]>
for bug report.
A bug was fixed in a routine that reads gzipped files. Thanks
to Achim Gaedke <[email protected]> for bug report.
Two API routines glp_get_it_cnt and glp_set_it_cnt were added.
Thanks to Joey Rios <[email protected]> for suggestion.
All obsolete GLPK API routines (prefixed with lpx) were removed
from the package.
A set of routines that simulate the old GLPK API (as defined
in 4.48) were added; see examples/oldapi/api/lpx.c. Thanks to
Jan Engelhardt <[email protected]> for suggestion.
A namespace bug was fixed in the SQL table drive module. Thanks
to Dennis Schridde <[email protected]> for bug report.
GLPK 4.52.1 (release date: Jul 28, 2013)
This is a bug-fix release.
A version information bug in Makefile.am was fixed. Thanks to
Sebastien Villemot <[email protected]> for bug report.
GLPK 4.52 (release date: Jul 18, 2013)
The clique cut generator was essentially reimplemented, and now
it is able to process very large and/or dense conflict graphs.
A simple rounding heuristic was added to the MIP optimizer.
Some bugs were fixed in the proximity search heuristic routine.
Thanks to Giorgio Sartor <[email protected]>.
New command-line option '--proxy [nnn]' was added to glpsol to
enable using the proximity search heuristic.
A bug (incorrect processing of LI column indicator) was fixed
in the mps format reading routine. Thanks to Charles Brixko for
bug report.
GLPK 4.51 (release date: Jun 19, 2013)
Singleton and dense phases were implemented on computing
LU-factorization with Gaussian elimination. The singleton phase
is a feature that allows processing row and column singletons
on initial elimination steps more efficiently. The dense phase
is a feature used on final elimination steps when the active
submatrix becomes relatively dense. It significantly reduces
the time needed, especially if the active submatrix fits in CPU
cache, and improves numerical accuracy due to full pivoting.
The API routine glp_adv_basis that constructs advanced initial
LP basis was replaced by an improved version, which (unlike the
old version) takes into account numerical values of constraint
coefficients.
The proximity search heuristic for MIP was included in the GLPK
integer optimizer glp_intopt. On API level the heuristic can be
enabled by setting the parameter ps_heur in glp_iocp to GLP_ON.
This feature is also available in the solver glpsol through
command-line option '--proxy'. Many thanks to Giorgio Sartor
<[email protected]> for contribution.
A bug was fixed that caused numerical instability in the FPUMP
heuristic.
GLPK 4.50 (release date: May 24, 2013)
A new version of LU-factorization routines were added.
Currently this version provides the same functionality as the
old one, however, the new version allows further improving.
Old routines for FHV-factorization used to update the basis
factorization were replaced by a new version conforming to the
new version of LU-factorization.
Some clarifications about using the name index routines were
added. Thanks to Xypron <[email protected]> for suggestion.
Some typos were corrected in the MathProg language reference.
Thanks to Jeffrey Kantor <[email protected]> for report.
A serious bug (out-of-range indexing error) was *tentatively*
fixed in the routine glp_relax4. Unfortunatly, this bug is
inherited from the original Fortran version of the RELAX-IV
code (for details please see ChangeLog), and since the code is
very intricate, the bug is still under investigation. Thanks to
Sylvain Fournier for bug report.
GLPK 4.49 (release date: Apr 16, 2013)
The new API routine glp_mincost_relax4, which is a driver to
relaxation method of Bertsekas and Tseng (RELAX-IV), was added
to the package. RELAX-IV is a code for solving minimum cost
flow problems. On large instances it is 100-1000 times faster
than the standard primal simplex method. Prof. Bertsekas, the
author of the original RELAX-IV Fortran code, kindly permitted
to include a C translation of his code in GLPK under GPLv3.
A bug (wrong dual feasibility test) was fixed in API routine
glp_warm_up. Thanks to David T. Price <[email protected]>
for bug report.
Obsolete API routine lpx_check_kkt was replaced by new routine
glp_check_kkt.
IMPORTANT: All old API routines whose names begin with 'lpx_'
were removed from API level and NO MORE AVAILABLE.
GLPK 4.48 (release date: Jan 28, 2013)
This is a maintainer release.
Some minor changes in API (glpk.h) were made. For details
please see ChangeLog.
Some bugs/typos were fixed. Thanks to
Raniere Gaia Costa da Silva,
Heinrich Schuchardt <[email protected]>, and
Robbie Morrison <[email protected]> for reports.
GLPK 4.47 (release date: Sep 09, 2011)
The new API routine glp_intfeas1 was added to the package.
This routine is a tentative implementation of the integer (0-1)
feasibility solver based on the CNF-SAT solver (which currently
is MiniSat). It may be used in the same way as glp_intopt to
find either any integer feasible solution or a solution, for
which the objective function is not worse than the specified
value. Detailed description of this routine can be found in the
document "CNF Satisfiability Problem", which is included in the
distribution (see doc/cnfsat.pdf).
The following two options were added to glpsol:
--minisat translate 0-1 feasibility problem to CNF-SAT
problem and solve it with glp_intfeas1/MiniSat
(if the problem instance is already in CNF-SAT
format, no translation is performed)
--objbnd bound add inequality obj <= bound (minimization) or
obj >= bound (maximization) to 0-1 feasibility
problem (this option assumes --minisat)
The paint-by-numbers puzzle model (pbn.mod) included in the
distribution is a nice example of the 0-1 feasibility problem,
which can be efficiently solved with glp_intfeas1/MiniSat. This
model along with a brief instruction (pbn.pdf) and benchmark
examples from <webpbn.com> encoded in GNU MathProg (*.dat) can
be found in subdirectory examples/pbn/.
The glpsol lp/mip solver was modified to bypass postprocessing
of MathProg models if the solution reported is neither optimal
nor feasible.
A minor bug in examples/Makefile.am was fixed to correctly
build glpk in a separate directory. Thanks to Marco Atzeri
<[email protected]> for bug report and patch.
GLPK 4.46 (release date: Aug 09, 2011)
The following new API routines were added:
glp_read_cnfsat read CNF-SAT problem data in DIMACS format
glp_check_cnfsat check for CNF-SAT problem instance
glp_write_cnfsat write CNF-SAT problem data in DIMACS format
glp_minisat1 solve CNF-SAT problem instance with MiniSat
The routine glp_minisat1 is a driver to MiniSat, a CNF-SAT
solver developed by Niklas Een and Niklas Sorensson, Chalmers
University of Technology, Sweden. This routine is similar to
the routine glp_intopt, however, it is intended to solve a 0-1
programming problem instance, which is the MIP translation of
a CNF-SAT problem instance.
Detailed description of these new API routines can be found in
the document "CNF Satisfiability Problem", which is included in
the distribution (see files doc/cnfsat.tex and doc/cnfsat.pdf).
The following new glpsol command-line options were added:
--cnf filename read CNF-SAT problem instance in DIMACS
format from filename and translate it to MIP
--wcnf filename write CNF-SAT problem instance in DIMACS
format to filename
--minisat solve CNF-SAT problem instance with MiniSat
solver
The zlib compression library (version 1.2.5) was ANSIfied,
modified according to GLPK requirements and included in the
distribution as an external software module. Thus, now this
feature is platform independent.
Some bugs were fixed in the SQL table driver. Thanks to Xypron
GLPK 4.45 (release date: Dec 05, 2010)
This is a bug-fix release.
Several bugs/typos were fixed. Thanks to
Xypron <[email protected]>,
Robbie Morrison <[email protected]>, and
Ali Baharev <[email protected]> for reports.
Some glpk documents was re-formatted and merged into a single
document. Now the glpk documentation consists of the following
three main documents (all included in the distribution):
GLPK: Reference Manual
GLPK: Graph and Network Routines
Modeling Language GNU MathProg: Language Reference
GLPK 4.44 (release date: Jun 03, 2010)
The following suffixes for variables and constraints were
implemented in the MathProg language:
.lb (lower bound),
.ub (upper bound),
.status (status in the solution),
.val (primal value), and
.dual (dual value).
Thanks to Xypron <[email protected]> for draft implementation
and testing.
Now the MathProg language allows comment records (marked by
'#' in the very first position) in CSV data files read with the
table statements. Note that the comment records may appear only
in the beginning of a CSV data file.
The API routine glp_cpp to solve the Critical Path Problem was
added and documented.
GLPK 4.43 (release date: Feb 20, 2010)
This is a maintainer release.
`configure.ac' was changed to allow building the package under
Mac OS and Darwin with ODBC support.
Thanks to Xypron <[email protected]> for suggestions and Noli
Sicad <[email protected]> for testing.
The SQL table driver was improved to process NULL data. Thanks
to Xypron <[email protected]>.
Some bugs were fixed in the LP/MIP preprocessor.
GLPK 4.42 (release date: Jan 13, 2010)
The following new API routines were added:
glp_check_dup check for duplicate elements in sparse
matrix
glp_sort_matrix sort elements of the constraint matrix
glp_read_prob read problem data in GLPK format
glp_write_prob write problem data in GLPK format
glp_analyze_bound analyze active bound of non-basic variable
glp_analyze_coef analyze objective coefficient at basic
variable
glp_print_ranges print sensitivity analysis report (this
routine replaces lpx_print_sens_bnds and
makes it deprecated)
For description of these new routines and the GLPK LP/MIP
format see a new edition of the reference manual included in
the distribution. (Chapter "Graph and network API routines" was
carried out from the main reference manual and included in the
distribution as a separate document.)
The following new command-line options were added to the stand-
alone solver glpsol:
--glp filename read problem data in GLPK format
--wglp filename write problem data in GLPK format
--ranges filename print sensitivity analysis report (this
option replaces --bounds)
Now all GLPK routines performing file I/O support special
filenames "/dev/stdin", "/dev/stdout", and "/dev/stderr", which
can be specified in the same way as regular filenames. This
feature is plaform-independent.
GLPK 4.41 (release date: Dec 21, 2009)
The following new API routies were added:
glp_transform_row transform explicitly specified row
glp_transform_col transform explicitly specified column
glp_prim_rtest perform primal ratio test
glp_dual_rtest perform dual ratio test
For description of these new routines see a new edition of the
reference manual included in the distribution.
The following API routines are deprecated: lpx_transform_row,
lpx_transform_col, lpx_prim_ratio_test, lpx_dual_ratio_test.
Some improvements were made in the MIP solver (glp_intopt).
The SQL table driver used to read/write data in MathProg models
was changed to allow multiple arguments separated by semicolon
in SQL statements. Thanks to Xypron <[email protected]>.
Two new options were added to the glpsol stand-alone solver:
--seed value (to initialize the pseudo-random number generator
used in MathProg models with specified value), and
--ini filename (to use a basis previously saved with -w option
as an initial basis on solving similar LP's).
Two new MathProg example models were included. Thanks to
Nigel Galloway <[email protected]> and Noli Sicad
<[email protected]> for contribution.
Scripts to build GLPK with Microsoft Visual Studio 2010 for
both 32-bit and 64-bit Windows were included. Thanks to Xypron
<[email protected]> for contribution and testing.
GLPK 4.40 (release date: Nov 03, 2009)
The following new API routines were added:
glp_del_vertices remove vertices from graph
glp_del_arc remove arc from graph
glp_wclique_exact find maximum weight clique with the exact
algorithm developed by Prof. P. Ostergard
glp_read_ccdata read graph in DIMACS clique/coloring
format
glp_write_ccdata write graph in DIMACS clique/coloring
format
For description of these new routines see a new edition of the
reference manual included in the distribution.
The hybrid pseudocost branching heuristic was included in the
MIP solver. It is available on API level (iocp.br_tech should
be set to GLP_BR_PCH) and in the stand-alone solver glpsol
(via the command-line option --pcost). This heuristic may be
useful on solving hard MIP instances.
The branching heuristic by Driebeck and Tomlin (used in the
MIP solver by default) was changed to switch to branching on
most fractional variable if an lower bound of degradation of
the objective is close to zero for all branching candidates.
A bug was fixed in the LP preprocessor (routine npp_empty_col).
Thanks to Stefan Vigerske <[email protected]> for the
bug report.
A bug was fixed and some improvements were made in the FPUMP
heuristic module. Thanks to Xypron <[email protected]>.
A bug was fixed in the API routine glp_warm_up (dual
feasibility test was incorrect in maximization case). Thanks to
Uday Venkatadri <[email protected]> for the bug report.
GLPK 4.39 (release date: Jul 26, 2009)
The following new API routines were added:
glp_warm_up "warm up" LP basis
glp_set_vertex_name assign (change) vertex name
glp_create_v_index create vertex name index
glp_find_vertex find vertex by its name
glp_delete_v_index delete vertex name index
glp_read_asnprob read assignment problem data in DIMACS
format
glp_write_asnprob write assignment problem data in DIMACS
format
glp_check_asnprob check correctness of assignment problem
data
glp_asnprob_lp convert assignment problem to LP
glp_asnprob_okalg solve assignment problem with the
out-of-kilter algorithm
glp_asnprob_hall find bipartite matching of maxumum
cardinality with Hall's algorithm
Also were added some API routines to read plain data files.
The API routines glp_read_lp and glp_write_lp to read/write
files in CPLEX LP format were re-implemented. Now glp_write_lp
correctly writes double-bounded (ranged) rows by introducing
slack variables rather than by duplicating the rows.
For description of these new routines see a new edition of the
reference manual included in the distribution.
The 'xfree(NULL)' bug was fixed in the AMD routines. Thanks to
Niels Klitgord <[email protected]> for bug report.
The message "Crashing..." was changed to "Constructing initial
basis..." due to suggestion by Thomas Kahle <[email protected]>.
Some typos were corrected in glpsol output messages. Thanks to
Xypron <[email protected]> for patch.
GLPK 4.38 (release date: May 02, 2009)
API routines glp_read_mps and glp_write_mps were improved.
Some improvements were made in the dual simplex routines.
Two external software modules AMD and COLAMD were included in
the distribution (for more details please see src/amd/README
and src/colamd/README). Now they are used in the interior-point
solver to reorder the matrix prior to Cholesky factorization.
API routine glp_ipt_status may return two new statuses due to
changes in the routine glp_interior. For details please see the
reference manual included in the distribution.
A minor bug was fixed in the graph/network routines. Thanks to
Nelson H. F. Beebe <[email protected]> for bug report.
GLPK 4.37 (release date: Mar 29, 2009)
The 0-1 Feasibility Pump heuristic was included in the GLPK
integer optimizer glp_intopt. On API level the heuristic can be
enabled by setting the parameter fp_heur in glp_iocp to GLP_ON.
This feature is also available in the solver glpsol through
command-line option '--fpump'. For more details please see the
reference manual included in the distribution.
The following new API routines were added:
glp_print_sol write basic solution in printable format
glp_print_ipt write interior-point solution in printable
format
glp_print_mip write MIP solution in printable format
glp_read_graph read (di)graph from plain text file
glp_write_graph write (di)graph to plain text file
glp_weak_comp find all weakly connected components
glp_strong_comp find all strongly connected components
The following API routines are deprecated: lpx_print_sol,
lpx_print_ips, lpx_print_mip, lpx_print_prob (the latter is
equivalent to glp_write_lp).
A bug was fixed in the interior-point solver (glp_interior) to
correctly compute dual solution components when the problem is
scaled.
The files configure.ac and Makefile.am were changed:
(a) to allow using autoreconf/autoheader;
(b) to allow building the package in a directory other than its
source directory.
Thanks to Marco Atzeri <[email protected]> for bug report.
An example model in the GNU MathProg language was added.
Thanks to Larry D'Agostino <Larry.D'[email protected]> for
contribution.
GLPK 4.36 (release date: Feb 06, 2009)
The following new API routines were added to the package:
glp_mincost_okalg find minimum-cost flow with out-of-kilter
algorithm
glp_maxflow_ffalg find maximal flow with Ford-Fulkerson
algorithm
For detailed description of these new routines and related data
structures see chapter "Graph and Network API Routines" in a new
edition of the reference manual included in the distribution.
The following two new command-line options were added to the
solver glpsol:
--mincost read min-cost flow data in DIMACS format
--maxflow read maximum flow data in DIMACS format
Duplicate symbols in the header glpk.h were removed to allow
using swig.
Thanks to Kelly Westbrooks <[email protected]> and
Nigel Galloway <[email protected]> for suggestion.
A minor defect was fixed in the routine glp_write_lp.
Thanks to Sebastien Briais <[email protected]> for bug report.
A minor bug was fixed in the SQL module.
Thanks to Xypron <[email protected]> for patch.
Some new example models in the GNU MathProg modeling language
were added. Thanks to Sebastian Nowozin <[email protected]> and
Nigel Galloway <[email protected]> for contribution.
GLPK 4.35 (release date: Jan 09, 2009)
The following new API routines were added to the package:
glp_create_graph create graph
glp_set_graph_name assign (change) graph name
glp_add_vertices add new vertices to graph
glp_add_arc add new arc to graph
glp_erase_graph erase graph content
glp_delete_graph delete graph
glp_read_mincost read minimum cost flow problem data in
DIMACS format
glp_write_mincost write minimum cost flow problem data in
DIMACS format
glp_mincost_lp convert minimum cost flow problem to LP
glp_netgen Klingman's network problem generator
glp_gridgen grid-like network problem generator
glp_read_maxflow read maximum flow problem data in DIMACS
format
glp_write_maxflow write maximum flow problem data in DIMACS
format
glp_maxflow_lp convert maximum flow problem to LP
glp_rmfgen Goldfarb's maximum flow problem generator
For detailed description of these new routines and related data
structures see chapter "Graph and Network API Routines" in a new
edition of the reference manual included in the distribution.
A minor change were made in the internal routine xputc. Thanks
to Luiz Bettoni <[email protected]> for suggestion.
A minor bug was fixed in the internal routine mpl_fn_time2str.
Thanks to Stefan Vigerske <[email protected]> for bug report.
GLPK 4.34 (release date: Dec 04, 2008)
The GNU MathProg modeling language was supplemented with three
new built-in functions:
gmtime obtaining current calendar time
str2time converting character string to calendar time
time2str converting calendar time to character string
(Thanks to Xypron <[email protected]>.)
For detailed description of these functions see Appendix A in
the document "Modeling Language GNU MathProg", a new edition of
which was included in the distribution.
A bug was fixed in the MIP solver. Thanks to Nigel Galloway
<[email protected]> for bug report.
A new makefile was added to build the GLPK DLL with Microsoft
Visual Studio Express 2008 for 64-bit Windows. Thanks to Xypron
<[email protected]> for contribution and testing.
GLPK 4.33 (release date: Oct 30, 2008)
The following new API routines were added to the package:
glp_copy_prob copy problem object content
glp_exact solve LP in exact arithmetic
(makes lpx_exact deprecated)
glp_get_unbnd_ray determine variable causing unboundedness
(makes lpx_get_ray_info deprecated)
glp_interior solve LP with interior-point method
(makes lpx_interior deprecated)
The following new API routines for processing models written in
the GNU Mathprog language were added to the package:
glp_mpl_alloc_wksp allocate the translator workspace
glp_mpl_read_model read and translate model section
glp_mpl_read_data read and translate data section
glp_mpl_generate generate the model
glp_mpl_build_prob build LP/MIP instance from the model
glp_mpl_postsolve postsolve the model
glp_mpl_free_wksp deallocate the translator workspace
(These routines make lpx_read_model deprecated.)
For description of all these new API routines see the reference
manual included in the distribution.
A crude implementation of CPLEX-like interface to GLPK API was
added to the package. Currently it allows using GLPK as a core
LP solver for Concorde, a well known computer code for solving
the symmetric TSP. For details see examples/cplex/README.
Some bugs were fixed in the SQL table driver. Thanks to Xypron
GLPK 4.32 (release date: Oct 03, 2008)
The following new features were included in the MIP solver
(the API routine glp_intopt):
* MIP presolver
* mixed cover cut generator
* clique cut generator
* Euclidean reduction of the objective value
Due to changes the routine glp_intopt may additionally return
GLP_ENOPFS, GLP_ENODFS, and GLP_EMIPGAP.
The API routines lpx_integer are lpx_intopt are deprecated,
since they are completely superseded by glp_intopt.
The following new branch-and-cut API routines were added:
glp_ios_row_attr determine additional row attributes
glp_ios_pool_size determine current size of the cut pool
glp_ios_add_row add constraint to the cut pool
glp_ios_del_row delete constraint from the cut pool
glp_ios_clear_pool delete all constraints from the cut pool
For description of these new routines see the reference manual
included in the distribution.
The stand-alone solver glpsol was changed to allow multiple
data files.
A new edition of the supplement "Using Data Tables in the GNU
MathProg Modeling Language" was included.
As usual, some bugs were fixed (in the MathProg translator).
Thanks to Xypron <[email protected]>.
GLPK 4.31 (release date: Sep 02, 2008)
The core LP solver based on the dual simplex method was
re-implemented and now it provides both phases I and II.
The following new API routines were added:
glp_scale_prob automatic scaling of problem data
glp_std_basis construct standard initial LP basis
glp_adv_basis construct advanced initial LP basis
glp_cpx_basis construct Bixby's initial LP basis
For description of these new routines see the reference manual
included in the distribution.
The following API routines are deprecated:
lpx_scale_prob, lpx_std_basis, lpx_adv_basis, lpx_cpx_basis.
Necessary changes were made in memory allocation routines to
resolve portability issues for 64-bit platforms.
New version of the routine lpx_write_pb to write problem data
in OPB (pseudo boolean format) was added to the package. Thanks
to Oscar Gustafsson <[email protected]> for the contribution.
Two new makefiles were added to build the package for 32- and
64-bit Windows with Microsoft Visual Studio Express 2008.
Thanks to Heinrich Schuchardt <[email protected]> (aka
Xypron) for the contribution and testing.
Two new makefiles were added to build the package with Digital
Mars C/C++ 8.50 and Open Watcom C/C++ 1.6 (for 32-bit Windows).
GLPK 4.30 (release date: Aug 13, 2008)
The core LP solver based on the primal simplex method was
re-implemented to allow its further improvements. Currently the
new version provides the same features as the old one, however,
it is a bit faster and more numerically stable.
Some changes were made in the MathProg translator to allow <,
<=, >=, and > on comparing symbolic values. Thanks to Heinrich
Schuchardt <[email protected]> for patches.
Internal routine set_d_eps in the exact LP solver was changed
to prevent approximation errors in case of integral data.
Thanks to Markus Pilz <[email protected]> for bug report.
GLPK 4.29 (release date: Jul 06, 2008)
The configure script was changed to disable all optional
features by default. For details please see file INSTALL.
The following new API routines were added:
glp_erase_prob erase problem object content
glp_read_mps read problem data in MPS format
glp_write_mps write problem data in MPS format
glp_read_lp read problem data in CPLEX LP format
glp_write_lp write problem data in CPLEX LP format
For description of these new routines see the reference manual
included in the distribution.
The following API routines are deprecated:
lpx_read_mps, lpx_read_freemps, lpx_write_mps,
lpx_write_freemps, lpx_read_cpxlp, and lpx_write_cpxlp.
Two bugs were fixed. Thanks to
Anne-Laurence Putz <[email protected]> and
Xypron <[email protected]> for bug report.
GLPK 4.28 (release date: Mar 25, 2008)
The iODBC and MySQL table drivers, which allows transmitting
data between MathProg model objects and relational databases,
were re-implemented to replace a static linking by a dynamic
linking to corresponding shared libraries.
Many thanks to Heinrich Schuchardt <[email protected]>
for the contribution, Rafael Laboissiere <[email protected]>
for useful advices concerning the shared library support under
GNU/Linux, and Vijay Patil <[email protected]> for testing
this feature under Windows XP.
A new optional feature was added to the package. This feature
is based on the zlib data compression library and allows GLPK
API routines and the stand-alone solver to read and write
compressed data files performing compression/decompression "on
the fly" (compressed data files are recognized by suffix `.gz'
in the file name). It may be useful in case of large MPS files
to save the disk space (up to ten times).
The `configure' script was re-implemented. Now it supports the
following specific options:
--with-gmp Enable using the GNU MP bignum library
--without-gmp Disable using the GNU MP bignum library
--with-zlib Enable using the zlib data compression
library
--without-zlib Disable using the zlib data compression
library
--enable-dl Enable shared library support (auto check)
--enable-dl=ltdl Enable shared library support (GNU)
--enable-dl=dlfcn Enable shared library support (POSIX)
--disable-dl Disable shared library support
--enable-odbc Enable using ODBC table driver
--disable-odbc Disable using ODBC table driver
--enable-mysql Enable using MySQL table driver
--disable-mysql Disable using MySQL table driver
For more details please see file INSTALL.
GLPK 4.27 (release date: Mar 02, 2008)
Three new table drivers were added to the MathProg translator:
xBASE built-in table driver, which allows reading and writing
data in .dbf format (only C and N fields are supported);
MySQL table driver, which provides connection to a MySQL
database;
iODBC table driver, which provides connection to a database
through ODBC.
The MySQL and iODBC table drivers were contributed to GLPK by
Heinrich Schuchardt <[email protected]>.
The table driver is a program module which allows transmitting
data between MathProg model objects and external data tables.
For detailed description of the table statement and table
drivers see the document "Using Data Tables in the GNU MathProg
Modeling Language" (file doc/tables.txt) included in the
distribution. Some examples which demonstrate using MySQL and
iODBC table drivers can be found in subdirectory examples/sql.
GLPK 4.26 (release date: Feb 17, 2008)
The table statement was implemented in the GNU MathProg
modeling language. This new feature allows reading data from
external tables into model objects such as sets and parameters
as well as writing results of computations to external tables.
A table is a (unordered) set of records, where each record
consists of the same number of fields, and each field is
provided with a unique symbolic name called the field name.
Currently the GLPK package has the only built-in table driver,
which supports tables in the CSV (comma-separated values) file
format. This format is very simple and supported by almost all
spreadsheets and database management systems.
Detailed description of the table statement and CSV format can
be found in file doc/tables.txt, included in the distribution.
GLPK 4.25 (release date: Dec 19, 2007)
A tentative implementation of Gomory's mixed integer cuts was
included in the branch-and-cut solver. To enable generating
Gomory's cuts the control parameter gmi_cuts passed to the
routine glp_intopt should be set to GLP_ON. This feature is
also available in the solver glpsol through command-line option
'--gomory'. For more details please see the reference manual
included in the distribution.
GLPK 4.24 (release date: Nov 21, 2007)
A tentative implementation of MIR (mixed integer rounding) cuts
was included in the MIP solver. To enable generating MIR cuts
the control parameter mir_cuts passed to the routine glp_intopt
should be set to GLP_ON. This feature is also available in the
stand-alone solver glpsol via command-line option '--mir'. For
more details please see the reference manual included in the
distribution.
The implementation is mainly based on the following two papers:
1. H. Marchand and L. A. Wolsey. Aggregation and mixed integer
rounding to solve MIPs. CORE discussion paper 9839, CORE,
Universite catholique de Louvain, June 1998.
2. G. Andreello, A. Caprara, and M. Fischetti. Embedding cuts
in a Branch&Cut framework. Preliminary draft, October 2003.
MIR cuts can be generated on any level of the search tree that
makes the GLPK MIP solver to be a real branch-and-cut solver.
A bug was fixed in the routine lpx_write_cpxlp. If a variable
x has upper bound and no lower bound, it should appear in the
bounds section as "-inf <= x <= u", not as "x <= u". Thanks to
Enric Rodriguez <[email protected]> for the bug report.
GLPK 4.23 (release date: Oct 28, 2007)
The following new API routines were added:
glp_read_sol read basic solution from text file
glp_write_sol write basic solution to text file
glp_read_ipt read interior-point solution from text file
glp_write_ipt write interior-point solution to text file
glp_read_mip read MIP solution from text file
glp_write_mip write MIP solution to text file
For description of these routines and corresponding file
formats see Chapter "API Routines", Section "Utility routines"
in the reference manual included in the distribution.
Advanced API routine glp_free_env was added. It may be used by
the application program to free all resources allocated by GLPK
routines.
The following three new command-line options were added to the
solver glpsol: