lemon-project-template-glpk: deps/glpk/NEWS comparison

lemon-project-template-glpk

comparison deps/glpk/NEWS @ 11:4fc6ad2fb8a6

Test GLPK in src/main.cc

author	Alpar Juttner <alpar@cs.elte.hu>
date	Sun, 06 Nov 2011 21:43:29 +0100
parents
children

comparison

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--1:000000000000
+:bd6dc4495aea
+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
+<marco.atzeri@gmail.com> 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
+<xypron.glpk@gmx.de>.
+GLPK 4.45 (release date: Dec 05, 2010)
+This is a bug-fix release.
+Several bugs/typos were fixed. Thanks to
+Xypron <xypron.glpk@gmx.de>,
+Robbie Morrison <robbie@actrix.co.nz>, and
+Ali Baharev <ali.baharev@gmail.com> 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 <xypron.glpk@gmx.de> 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 <xypron.glpk@gmx.de> for suggestions and Noli
+Sicad <nsicad@gmail.com> for testing.
+The SQL table driver was improved to process NULL data. Thanks
+to Xypron <xypron.glpk@gmx.de>.
+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 <xypron.glpk@gmx.de>.
+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 <nigel_galloway@operamail.com> and Noli Sicad
+<nsicad@gmail.com> for contribution.
+Scripts to build GLPK with Microsoft Visual Studio 2010 for
+both 32-bit and 64-bit Windows were included. Thanks to Xypron
+<xypron.glpk@gmx.de> 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 <stefan@math.hu-berlin.de> for the
+bug report.
+A bug was fixed and some improvements were made in the FPUMP
+heuristic module. Thanks to Xypron <xypron.glpk@gmx.de>.
+A bug was fixed in the API routine glp_warm_up (dual
+feasibility test was incorrect in maximization case). Thanks to
+Uday Venkatadri <Uday.Venkatadri@dal.ca> 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 <niels@bu.edu> for bug report.
+The message "Crashing..." was changed to "Constructing initial
+basis..." due to suggestion by Thomas Kahle <tom111@gmx.de>.
+Some typos were corrected in glpsol output messages. Thanks to
+Xypron <xypron.glpk@gmx.de> 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 <beebe@math.utah.edu> 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 <marco_atzeri@yahoo.it> for bug report.
+An example model in the GNU MathProg language was added.
+Thanks to Larry D'Agostino <Larry.D'Agostino@gmacrescap.com> 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 <kellywestbrooks@yahoo.com> and
+Nigel Galloway <nigel_galloway@operamail.com> for suggestion.
+A minor defect was fixed in the routine glp_write_lp.
+Thanks to Sebastien Briais <sbriais@free.fr> for bug report.
+A minor bug was fixed in the SQL module.
+Thanks to Xypron <xypron.glpk@gmx.de> for patch.
+Some new example models in the GNU MathProg modeling language
+were added. Thanks to Sebastian Nowozin <nowozin@gmail.com> and
+Nigel Galloway <nigel_galloway@operamail.com> 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 <bettoni@cpgei.ct.utfpr.edu.br> for suggestion.
+A minor bug was fixed in the internal routine mpl_fn_time2str.
+Thanks to Stefan Vigerske <stefan@vigerske.de> 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 <xypron.glpk@gmx.de>.)
+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
+<nigel_galloway@operamail.com> 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
+<xypron.glpk@gmx.de> 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
+<xypron.glpk@gmx.de>.
+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 <xypron.glpk@gmx.de>.
+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 <oscarg@isy.liu.se> 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 <heinrich.schuchardt@gmx.de> (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 <heinrich.schuchardt@gmx.de> 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 <pilz@cs.uni-bonn.de> 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 <anne-laurence.putz@eurodecision.com> and
+Xypron <xypron.glpk@gmx.de> 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 <heinrich.schuchardt@gmx.de>
+for the contribution, Rafael Laboissiere <rafael@debian.org>
+for useful advices concerning the shared library support under
+GNU/Linux, and Vijay Patil <vijay.patil@gmail.com> 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 <heinrich.schuchardt@gmx.de>.
+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 <erodri@lsi.upc.edu> 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:
+--mipgap tol    set relative MIP gap tolerance
+-r filename     read solution from filename
+-w filename     write solution to filename
+GLPK 4.22 (release date: Sep 19, 2007)
+This is a maintainer release.
+A bug was fixed in the MIP preprocessor (ios_preprocess_node).
+Thanks to Roberto Bagnara <bagnara@cs.unipr.it> (Department of
+Mathematics, University of Parma, Italy) for the bug report.
+A bug was fixed in the MIP preprocessor (col_implied_bounds),
+due to which constraint coefficients with small magnitude could
+lead to wrong implied bounds of structural variables.
+A similar bug was fixed in the routine reduce_bounds.
+A bug was fixed in the routines glp_set_mat_row and
+glp_set_mat_col. (The bug appeared due to incorrect removing
+zero elements from the row/column lists.)
+A bug was fixed in the API routines lpx_read_mps and
+lpx_read_freemps, due to which bounds of type LI specified in
+BOUNDS section were incorrectly processed.
+A call to standard function vsprintf was replaced by a call to
+vsnprintf for security reasons. Many thanks to Peter T. Breuer
+<ptb@inv.it.uc3m.es> and Rafael Laboissiere <rafael@debian.org>.
+GLPK 4.21 (release date: Aug 28, 2007)
+Additional reasons for calling the callback routine used in the
+MIP solver (glp_intopt) were introduced. Currently the following
+reasons are supported:
+* request for subproblem selection
+* request for preprocessing
+* request for row generation
+* request for heuristic solution
+* request for cut generation
+* request for branching
+* better integer solution found
+A basic preprocessing component used to improve subproblem
+formulations by tightening bounds of variables was included in
+the MIP solver. Depending on the control parameter pp_tech
+passed to the routine glp_intopt the preprocessing can be
+performed either on the root level or on all levels (default)
+or can be disabled.
+Backtracking heuristic used by default in the MIP solver was
+changed to the "best local bound".
+For more details see Chapter "Advanced API routines", Section
+"Branch-and-bound interface routines" in a new edition of the
+reference manual included in the distribution.
+GLPK 4.20 (release date: Jul 26, 2007)
+API routine lpx_integer was replaced by API routine glp_intopt,
+which provides equivalent functionality and additionally allows
+the application to control the solution process by means of the
+user-written callback routine, which is called by the solver at
+various points of the branch-and-bound algorithm. Besides, the
+new MIP solver allows generating "lazy" constraints and cutting
+planes on all levels of the branch-and-bound tree, not only on
+the root level. The routine lpx_integer is also still available
+for the backward compatibility.
+The following new advanced API routines, which may be called
+from the B&B callback routine, were included in the package:
+glp_ios_reason     determine reason for calling callback
+routine
+glp_ios_get_prob   access the problem object
+glp_ios_tree_size  determine size of the branch-and-bound tree
+glp_ios_curr_node  determine current active subproblem
+glp_ios_next_node  determine next active subproblem
+glp_ios_prev_node  determine previous active subproblem
+glp_ios_up_node    determine parent subproblem
+glp_ios_node_level determine subproblem level
+glp_ios_node_bound determine subproblem local bound
+glp_ios_mip_gap    compute relative MIP gap
+glp_ios_heur_sol   provide solution found by heuristic
+glp_ios_terminate  terminate the solution process
+For description of these routines see Chapter "Advanced API
+routines", Section "Branch-and-bound interface routines" in a
+new edition of the reference manual, which was included in the
+distribution.
+Old version of the integer optimization suite (IOS) as well as
+TSP solver tspsol based on it are no longer supported and were
+removed from the package.
+A minor error in the MIP presolver was fixed; thanks to Graham
+Rockwell <bionomicron@gmail.com> for the bug report.
+GLPK 4.19 (release date: Jul 05, 2007)
+The principal change is upgrading to GPLv3.
+A serious bug in the routine glp_del_cols was fixed; thanks to
+Cedric[FR] <fox2113@wanadoo.fr> for the bug report. The bug
+appeared because on deleting non-basic columns the basis header
+remained valid, however, contained invalid (old) column ordinal
+numbers.
+A new advanced API routine glp_mem_limit was added.
+The case GLP_EBOUND was added to the routine lpx_simplex.
+Thanks to Cameron Kellough <Cameron.Kellough@sri.com> for the
+bug report.
+An API routine lpx_write_pb to write the problem instance in
+OPB (pseudo boolean) format format was added. Thanks to Oscar
+Gustafsson <oscarg@isy.liu.se> for the contribution.
+Two new options --wpb and --wnpb were added to glpsol to write
+the problem instance in OPB format.
+GLPK 4.18 (release date: Jun 25, 2007)
+The following new API routines were added:
+glp_set_rii        set (change) row scale factor
+glp_set_sjj        set (change) column scale factor
+glp_get_rii        retrieve row scale factor
+glp_get_sjj        retrieve column scale factor
+glp_simplex        solve LP problem with the simplex method
+(this routine replaces lpx_simplex, which is
+also available for backward compatibility)
+glp_init_smcp      initialize simplex method control params
+glp_bf_exists      check if the basis factorization exists
+glp_factorize      compute the basis factorization
+glp_bf_updated     check if the basis factorization has been
+updated
+glp_get_bfcp       retrieve basis factorization control params
+glp_set_bfcp       change basis factorization control params
+glp_get_bhead      retrieve the basis header information
+glp_get_row_bind   retrieve row index in the basis header
+glp_get_col_bind   retrieve column index in the basis header
+glp_ftran          perform forward transformation
+glp_btran          perform backward transformation
+For description of all these routines see a new edition of the
+reference manual included in the distribution.
+Type names ulong_t and uldiv_t were changed to glp_ulong and
+glp_uldiv to avoid conflicts with standard type names on some
+platforms. Thanks to Boris Wirtz <Boris.Wirtz@uni-oldenburg.de>
+for the bug report.
+Some new examples in the MathProg language were added. Thanks
+to Sebastian Nowozin <nowozin@gmail.com>.
+GLPK 4.17 (release date: May 26, 2007)
+API routines glp_set_mat_row, glp_set_mat_col, and glp_load_mat
+were modified to allow zero constraint coefficients (which are
+not stored in the constraint matrix). Note that constraint
+coefficients with duplicate row/column indices are not allowed.
+Another form of LP basis factorization was implemented in the
+package. It is based on LU-factorization of an initial basis
+and Schur complement to reflect changes in the basis. Currently
+the implementation is incomplete and provides only updating the
+factorization on replacing a column of the basis matrix. On API
+level the user can set the control parameter LPX_K_BFTYPE to
+choose between the folloiwng forms of LP basis factorization to
+be used in the simplex method routines:
+1) LU + Forrest-Tomlin update;
+2) LU + Schur complement + Bartels-Golub update;
+3) LU + Schur complement + Givens rotation update.
+The GLPK implementation is similar to LUSOL/LUMOD developed by
+Michael A. Saunders.
+The user can choose the form of LP basis factorzation used by
+the simplex method routines by specifying the folloiwng options
+of glpsol: --luf, --cbg, --cgr.
+GLPK 4.16 (release date: May 05, 2007)
+A number of basic GLPK API routines, which now are in the
+stable stable, were renamed to be prefixed with 'glp_'. Note
+that all these routines are available via their old names
+prefixed with 'lpx_' that keeps the downward compatibility with
+older versions of the package.
+Three new GLPK API routines were added to the package:
+glp_version, glp_term_hook, and glp_mem_usage; for more details
+see a new edition of the GLPK reference manual included in the
+distribution. The routine glp_version reports the actual version
+of the GLPK library and also can be used (along with the header
+glpk.h) in Autotools specification files to check if the GLPK
+library has been installed.
+The header glpk.h was changed to conform to C++ environment.
+GLPK 4.15 (release date: Feb 18, 2007)
+Autotools specification files (configure.ac, Makefile.am) were
+changed to use GNU Libtool. This allows building the static as
+well as shared GLPK library.
+GLPK 4.14 (release date: Feb 05, 2007)
+Now GLPK conforms to ILP32, LLP64, and LP64 programming models
+(the latter seems to be the ultimate choice regarding 64-bit
+architectures). Note that GLPK itself is a 32-bit application,
+and the conformity only means that the package works correctly
+on all these arenae. Nevertheless, on 64-bit platforms it is
+possible to use more than 4GB of memory, if necessary.
+GLPK 4.13 (release date: Nov 13, 2006)
+A tentative implementation of the "exact" simplex method based
+on bignum (rational) arithmetic was included in the package.
+On API level this new feature is available through the routine
+lpx_exact, which is similar to the routine lpx_simplex.
+In the solver glpsol this feature 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 4.12 (release date: Nov 08, 2006)
+A tentative implementation of some simplex method routines
+based on exact (bignum) arithmetic was included in the package.
+Currently these routines provide computing LU-factorization of
+the basis matrix and computing components of basic solution.
+These routines were used to implement a routine, which checks
+primal and dual feasibility of basic solution exactly, i.e. in
+rational numbers, without round-off errors. In glpsol this
+feature is available through the command-line option --xcheck.
+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). Using GMP
+makes computations 100-200 times faster.
+GLPK 4.11 (release date: Jul 25, 2006)
+Three new built-in functions in the modeling language were
+implemented: card (cardinality of set), length (length of
+character string), and substr (substring of character string).
+Another improvement concerns the printf statement which now
+allows redirecting its output to a specified file. These new
+features are illustrated in example models crypto.mod and
+graph.mod included in the distribution. For more details see
+the document "Modeling Language GNU MathProg".
+Four batch files (along with corresponding makefiles) were
+included in the distribution to simplify building GLPK under
+MS Windows; see them in subdirectory 'w32'.
+GLPK 4.10 (release date: May 11, 2006)
+Cutting planes of two new classes were implemented: mixed cover
+cuts and clique cuts. On API level this feature can be enabled
+by setting control parameter LPX_K_USECUTS passed to the routine
+lpx_intopt. In glpsol this feature is available through the
+command-line options --cover and --clique. For more details see
+the reference manual.
+Now the routines lpx_read_mps and lpx_read_freemps support LI
+bound type. It is similar to LO, however, indicates the column
+as of integer kind.
+GLPK 4.9 (release date: Jan 17, 2006)
+An advanced MIP solver was implemented. It includes:
+- basic presolving technique (removing free, singleton and
+redundant rows, improving bounds of columns, removing fixed
+columns, reducing constraint coefficents);
+- generating cutting planes to improve LP relaxation (currently
+only Gomory's mixed integer cuts are implemented);
+- using the branch-and-bound method to solve resultant MIP;
+- recovering solution of the original MIP.
+The solver is available on API level via the routine lpx_intopt
+(see the reference manual). It is similar to the routine
+lpx_integer, however, does not require initial solution of LP
+relaxation.
+The solver is also available in the command-line utility glpsol
+via two options: --intopt (only presolving) and --cuts (assumes
+--intopt plus generating cuts).
+Note that efficiency of the MIP solver strongly depends on the
+internal structure of the problem to be solved. For some hard
+instances it is very efficient, but for other instances it may
+be significantly worse than the standard branch-and-bound.
+For some comparative benchmarks see doc/bench1.txt.
+Well, what else...
+Three built-in functions were added to MathProg: sin, cos, and
+atan (the latter allows one or two arguments).
+Some bugs were fixed.
+Several new examples in MathProg were included: color.mod
+(graph coloring problem), tsp.mod (traveling salesman problem),
+and pbn.mod (paint-by-numbers puzzle).
+GLPK 4.8 (release date: Jan 12, 2005)
+Core simplex method and interior-point method routines were
+re-implemented and now they use a new, "storage-by-rows" sparse
+matrix format (unlike previous versions where linked lists were
+used to represent sparse matrices). For details see ChangeLog.
+Also a minor bug was fixed in API routine lpx_read_cpxlp.
+GLPK 4.7 (release date: Aug 23, 2004)
+Now GLPK supports free MPS format. Two new API routines
+lpx_read_freemps (to read problem data in free MPS format) and
+lpx_write_freemps (to write problem data in free MPS format)
+were added. This feature is also available in the solver glpsol
+via new command-line options --freemps and --wfreemps. For more
+details see the GLPK reference manual.
+API routines lpx_read_cpxlp and lpx_write_cpxlp for reading and
+writing problem data in CPLEX LP format were re-implemented to
+allow long symbolic names (up to 255 characters).
+The following three modules were temporarily removed from the
+GLPK distribution due to licensing problems: DELI (an interface
+module to Delphi), GLPKMEX (an interface module to Matlab), and
+JNI (an interface module to Java).
+GLPK 4.6 (release date: Aug 04, 2004)
+Three new statements were implemented in the GNU MathProg
+language: solve, printf, and for. Their detailed description can
+be found in the GLPK documentation included in the distribution.
+(See also a sample model, examples/queens.mod, which illustrates
+using these new statements.)
+Two new API routines were added to the package: lpx_read_prob
+and lpx_write_prob. They allow reading/writing problem data in
+GNU LP low-level text format.
+Three new command-line options were implemented in the LP/MIP
+solver glpsol: --glp (to read problem data in GNU LP format),
+--wglp (to write problem data in GNU LP format), and --name (to
+change problem name). Now glpsol also supports processing models
+where the new statements (see above) are used.
+A new version of GLPKMEX, a Matlab MEX interface to GLPK, was
+included. For more details see contrib/glpkmex/ChangeLog.
+GLPK 4.5 (release date: Jul 19, 2004)
+The branch-and-bound solver was completely re-implemented.
+Some modifications were made in memory allocation routines that
+allows using the package on 64-bit platforms.
+For more details see ChangeLog.
+GLPK 4.4 (release date: Jan 17, 2004)
+All API routines were re-implemented using new data structures.
+The new implementation provides the same specifications and
+functionality of API routines as the old one, however, it has
+some important advantages, in particular:
+* linked lists are used everywhere that allows creating and
+modifying the problem object as efficiently as possible
+* all data stored in the problem object are non-scaled (even if
+the internal scaling is used) that prevents distortion of the
+original problem data
+* solution components obtained by the solver remain available
+even if the problem object has been modified
+* no solver-specific data are used in the new data structures
+that allows attaching any external lp/mip solver using GLPK
+API as an uniform interface
+Note that some API routines became obsolete being replaced by
+new, more convenient routines. These obsolete routines are kept
+for backward compatibility, however, they will be removed in
+the future. For more details please see ChangeLog and the GLPK
+Reference Manual.
+New edition of the GLPK Reference Manual was included in the
+distribution.
+GLPKMEX, a Matlab MEX interface to GLPK package, contributed by
+Nicolo Giorgetti <giorgetti@dii.unisi.it> was included in the
+distribution.
+GLPK FAQ contributed by Harley Mackenzie <hjm@bigpond.com> was
+included in the distribution.
+GLPK 4.3 (release date: Dec 12, 2003)
+The bug, due to which the standard math library is not linked
+on building the package on some platforms, was fixed.
+The following new built-in functions were added to the MathProg
+language: round, trunc, Irand224, Uniform01, Uniform, Normal01,
+Normal. For details see the language description.
+The MathProg syntax was changed to allow writing 'subj to' that
+means 'subject to'.
+The new api routine lpx_get_ray_info was added. It is intended
+to determine which (non-basic) variable causes unboundness. For
+details see the reference manual.
+The module glpmps.c was changed to avoid compilation errors on
+building the package on Mac OS X.
+Several typos was fixed and some new material was added to the
+GLPK documentation.
+GLPK 4.2 (release date: Nov 14, 2003)
+A preliminary implementation of the Integer Optimization Suite
+(IOS) was included in the package. The Branch-and-Cut Framework
+being completely superseded by IOS was removed from the package.
+New API routine lpx_print_sens_bnds intended for bounds
+sensitivity analysis was contributed to GLPK by Brady Hunsaker
+<hunsaker@engr.pitt.edu>. This function is also available in
+the solver glpsol (via command-line option --bounds).
+An improved version of GLPK JNI (Java Native Interface) was
+contributed by Chris Rosebrugh <cpr@pobox.com>.
+GLPK DELI (Delphi Interface) was contributed by Ivo van Baren
+<i.van.baren@freeler.nl>.
+Several makefiles were added to allow compiling GLPK on some
+non-GNU 32-bit platforms:
+* Windows single-threaded static library, Visual C++ 6.0
+* Windows multi-threaded dynamic library, Visual C++ 6.0
+* Windows single-threaded static library, Borland C++ 5.2
+* DOS single-threaded static library, Digital Mars C++ 7.50
+And, of course, some bugs were fixed.
+For more details see ChangeLog.
+GLPK 4.1 (release date: Aug 23, 2003)
+Some improvements were made in the lp/mip solver routines and
+several bugs were fixed in the model translator.
+For more details see ChangeLog.
+GLPK 4.0 (release date: May 06, 2003)
+Now GLPK supports the GNU MathProg modeling language, which is
+a subset of the AMPL modeling language.
+The document "GLPK: Modeling Language GNU MathProg" included in
+the distribution is a complete description of GNU MathProg. (See
+the files lang.latex, lang.dvi, and lang.ps in the subdirectory
+'doc'. See also some examples in the subdirectory 'sample'.)
+New version of the solver glpsol, which supports models written
+in GNU MathProg, was implemented. (Brief instructions how to use
+glpsol can be found in the GNU MathProg documentation.)
+The GLPK/L modeling language is no more supported. The reason is
+that GNU MathProg being much more powerful completely supersedes
+all features of GLPK/L.
+GLPK 3.3 (release date: Mar 25, 2003)
+LP PRESOLVER
+------------
+Now the routine lpx_simplex (which is a driver to the simplex
+method for solving LP) is provided with the built-in LP
+presolver, which is a program that transforms the original LP
+problem to an equivalent LP problem, which may be easier for
+solving with the simplex method than the original one. Once the
+transformed LP has been solver, the presolver transforms its
+basic solution back to a corresponding basic solution of the
+original problem. For details about this feature please see the
+GLPK reference manual.
+Currently the LP presolver implements the following features:
+* removing empty rows;
+* removing empty columns;
+* removing free rows;
+* removing fixed columns;
+* removing row singletons, which have the form of equations;
+* removing row singletons, which have the form of inequalities;
+* removing column singletons, which are implied slack variables;
+* fixing and removing column singletons, which are implied free
+variables;
+* removing forcing rows that involves fixing and removing the
+corresponding columns;
+* checking for primal and dual infeasibilities.
+The LP presolver is also used by default in the stand-alone
+program glpsol. In order *not* to use it, the option --nopresol
+should be specified in the command-line.
+CHANGES IN GLPK/L
+-----------------
+The syntax and semantics of the GLPK/L modeling language was
+changed to allow declaration of "interval" sets. This means that
+now the user can declare a set, for example, as:
+set task = [8:11];
+that is exactly equivalent to the following declaration:
+set task = (task_8, task_9, task_10, task_11);
+For details see the language description.
+JAVA INTERFACE
+--------------
+Now GLPK includes the package GLPK JNI (Java Native Interface)
+that implements Java binding for GLPK. It allows Java programs
+to utilize GLPK in solving LP and MIP problems. For details see
+a brief user's guide in the subdirectory contrib/java-binding.
+This package was developed and programmed by Yuri Victorovich
+<yuri@gjt.org>, who contributed it to GLPK.
+GLPK 3.2.4 (release date: Feb 18, 2003)
+This is a bug-fix release. For details see ChangeLog.
+GLPK 3.2.3 (release date: Nov 11, 2002)
+A new implementation of the api routine lpx_integer which now
+is based on the b&b driver (which is based on the implicit
+enumeration suite) was included in the package. This new
+implementation has exactly the same functionality as the old
+version, so all changes are transparent to the api user.
+Four new api routines were included in the package:
+lpx_check_kkt checks Karush-Kuhn-Tucker optmality conditions;
+lpx_read_bas reads predifined basis in MPS format;
+lpx_write_bas writes current basis in MPS format;
+lpx_write_lpt writes problem data in CPLEX LP format.
+Also other minor improvements were made (for details see the
+file 'ChangeLog').
+GLPK 3.2.2 (release date: Oct 14, 2002)
+The api routine lpx_read_lpt was included in the package. It
+is similar to the routine lpx_read_mps and intended to read
+LP/MIP data prepared in CPLEX LP format. Description of this
+format is given in the GLPK reference manual, a new edition of
+which was also included in the distribution (see the files
+'refman.latex', 'refman.dvi', 'refman.ps' in the subdirectory
+'doc'). In order to use data files in CPLEX LP format with the
+solver glpsol the option '--lpt' should be specified in the
+command line.
+Several bugs were fixed and some minor improvements were made
+(for details see the file 'ChangeLog').
+GLPK 3.2.1 (release date: Aug 12, 2002)
+Now GLPK includes a preliminary implementation of the
+branch-and-cut framework, which is a set of data structures and
+routines intended for developing branch-and-cut methods for
+solving mixed-integer and combinatorial optimization problems.
+Detailed decsription of the branch-and-cut framework is given in
+the document "GLPK: A Preliminary Implementation of the
+Branch-And-Cut Framework" included in the distribution (see the
+file 'brcut.txt' in the subdirectory 'doc').
+In order to illustrate how the GLPK branch-and-cut framework
+can be used for solving a particular optimization problem there
+is an example included in the package. This is a stand-alone
+program, TSPSOL, which is intended for solving to optimality the
+symmetric Traveling Salesman Problem (TSP), a classical problem
+of the combinatorial optimization (see the file 'tspsol.c' in
+the subdirectory 'sample').
+GLPK 3.2 (release date: Jul 15, 2002)
+New edition of the document "GLPK: Reference Manual" was
+included (see the files 'refman.latex', 'refman.dvi', and
+'refman.ps' in the subdirectory 'doc').
+New edition of the document "GLPK: Modeling Language GLPK/L" was
+included (see the files 'lang.latex', 'lang.dvi', and 'lang.ps'
+in the subdirectory 'doc').
+The following new API routines were added to the package:
+lpx_transform_row (transform explicitly specified row);
+lpx_transform_col (transform explicitly specified column);
+lpx_prim_ratio_test (perform primal ratio test);
+lpx_dual_ratio_test (perform dual ratio test);
+lpx_interior (solve LP problem using interior point method);
+lpx_get_ips_stat (query status of interior point solution);
+lpx_get_ips_row (obtain row interior point solution);
+lpx_get_ips_col (obtain column interior point solution);
+lpx_get_ips_obj (obtain interior point value of obj.func.);
+lpx_read_lpm (read LP/MIP model written in GLPK/L);
+lpx_write_mps (write problem data using MPS format);
+lpx_print_ips (print interior point solution).
+Detailed description of all these new API routines are given in
+the new edition of the reference manual.
+New version of the stand-alone solver glpsol (which is based on
+the new API) was implemented.
+So long as the new API (introduced in glpk 3.0) now provides
+all the functions, which were provided by the old API, the old
+API routines were removed from the package at all.
+GLPK 3.1 (release date: May 27, 2002)
+A preliminary implementation of new API routines was completed
+and included in the package.
+These new API routines provide much more flexible interaction
+between the application program, LP/MIP problem instances, and
+solver routines. Based on completely changed data structures
+they are, however, similar to the API routines and provide the
+same functionality. Please note that three routines, namely,
+solving LPs using interior point method, reading model written
+in the GLPK/L modeling language, and writing problem data in
+the MPS format, are not implemented in the new API, however,
+these routines are planned to be implemented in the next version
+of the package.
+A description of the new API routines is given in the document
+"GLPK Reference Manual", a draft edition of which is included
+in the package (see the files 'refman.latex', 'refman.dvi', and
+'refman.ps' in the subdirectory 'doc').
+Although the old API routines are kept in the package, they are
+no longer supported and will be removed in the future.
+GLPK 3.0.8 (release date: May 13, 2002)
+A preliminary implementation of new API routines was included
+in the package. These new API routines are intended to provide
+much more flexible interaction between the application program,
+LP/MIP problem and solver routines. See the document "New GLPK
+API Routines" (the file 'newapi.txt' in the subdirectory 'doc')
+also included in the package.
+The api routines glp_simplex2, glp_call_ipm1, glp_call_bbm1 were
+renamed, respectively, to glp_simplex, glp_interior, glp_integer
+in order to reflect changes in implementation. The api routines
+glp_call_rsm1, glp_simplex1, glp_pivot_in, glp_pivout_out were
+removed from the package since they are completely supreseded by
+the new API routines (however, these routines still can be found
+in the subdirectory 'oldsrc'). Please consult a new edition of
+the document "GLPK User's Guide" about all these changes in the
+existing api routines.
+The document "GLPK Library Reference" was removed from the
+package (into the subdirectory 'oldsrc') since it describes the
+obsolete library routines, most of which are no longer used.
+GLPK 3.0.7 (release date: Apr 22, 2002)
+A new, more efficient implementation of the primal/dual simplex
+method was included in the package. Due to some improvements the
+simplex-based solver allows solving many LP problems faster and
+provides more reliable results. Note that the new implementation
+is currently incomplete and available only via the api routine
+glp_simplex2.
+All the changes are transparent on API level.
+GLPK 3.0.6 (release date: Mar 28, 2002)
+New version of LU-factorization and basis maintenance routines
+(based on Forrest-Tomlin updating technique) was implemented.
+Since these new routines functionally supersede some routines
+(which implement other forms of the basis matrix) and make them
+obsolete, the latter were removed from the package (they still
+can be found in the subdirectory 'oldsrc').
+All the changes are transparent on API level.
+GLPK 3.0.5 (release date: Jan 29, 2002)
+New edition of the document "GLPK User's Guide" was included in
+the distribution. Now it describes all additional API routines,
+which were recently added to the package.
+Structure of the package was re-organized in order to make its
+maintenance easier (all small files in the subdurectory 'source'
+were merged in bigger units). These changes are transparent for
+the user.
+GLPK 3.0.4 (release date: Dec 10, 2001)
+A new, more efficient implementation of the two-phase primal
+simplex method was included in the package. Due to some new
+features (an advanced initial basis, projected steepest edge,
+recursive updating values and reduced costs) the new LP solver
+is faster and numerically more stable than the old one.
+The new LP solver is available as API routine glp_simplex2 and
+has the same purpose as API routine glp_call_rsm1. For detailed
+specification see the file 'newapi.txt' in the directory 'doc'.
+Now the new LP solver is also used by default to solve an
+initial LP problem in the branch-and-bound routine glp_call_bbm1
+instead the routine rsm1_driver. Note that the branch-and-bound
+procedure itself is still based on rsm1_driver.
+The new LP solver is also used as default solver in GLPSOL for
+solving LP and MIP problems. In order to choose the old solver
+the option '--old-sim' can be specified in the command line.
+GLPK 3.0.3 (release date: Oct 03, 2001)
+Some minor changes were made in the simplex method routines in
+order to improve numerical stability of the method.
+GLPK 3.0.2 (release date: Sep 24, 2001)
+A new implementation of the basis maintaining routines was
+included in the package. These routines, which are based on so
+called FHV-factorization (a variety of LU-factorization) of the
+basis matrix and Gustavson's data structures, allows performing
+the main operations faster at the expense of some worsening
+numerical accuracy.
+AFI (Advanced Form of the Inverse), which is the form of the
+basis matrix based on FHV-factorization, is available via the
+parameter form = 3 (on API level) or via the option --afi (in
+GLPSOL solver).
+GLPK 3.0.1 (release date: Aug 01, 2001)
+Old GLPK API routines have been removed from the package.
+New GLPK API routines were added:
+- scaling routines;
+- a routine for writing problem data in MPS format;
+- a comprehensive driver to the simplex method;
+- basis maintaining routines.
+A description of the new API routines is given in the document
+"Additional GLPK API Routines". This document is included into
+the distribution in plain text format (see the file 'newapi.txt'
+in the subdirectory 'doc').
+Now the distribution includes a non-trivial example of using
+GLPK as a base LP solver for Concorde, a well known program that
+solves Traveling Salesman Problem (TSP). For further details see
+comments in the file 'sample/lpglpk30.c'.
+GLPK 3.0 (release date: Jul 19, 2001)
+Now GLPK is provided with new API, which being more flexible
+can be used in more complex algorithmic schemes.
+New edition of the document "GLPK User's Guide" is included in
+the distribution. Now it completely corresponds to the new GLPK
+API routines.
+Old API routines are not removed yet from the package, however
+they became obsolete and therefore should not be used. Since now
+the header glpk.h corresponds to new API, in order to compile
+existing programs that use old GLPK API routines the statement
+#define GLP_OLD_API
+should be inserted before the statement
+#include "glpk.h"
+GLPK 2.4.1 (release date: Jun 14, 2001)
+The document "Modeling language GLPK/L" is included into the
+distribution in texinfo format.
+New edition of the document "GLPK User's Guide" is included in
+the distribution. Now it describes all additional API routines
+which were recently added to the package.
+GLPK 2.4 (release date: May 10, 2001)
+Now GLPK includes an implementation of a preliminary version
+of the GLPK/L modeling language. This language is intended for
+writing mathematcal programming models. The name GLPK/L is
+derived from GNU Linear Programming Kit Language.
+A brief description of the GLPK/L language is given in the
+document "GLPK/L Modeling Language: A Brief Description". This
+document is included into the distribution in plain text format
+(see the file 'language.txt' in the subdirectory 'doc').
+The language processor (which is a program that analyzes model
+description written in GLPK/L and translates it to internal data
+structures) is available as the GLPK API routine.
+The stand-alone solver GLPSOL now is able: a) to process model
+descriptions written in the GLPK/L language; b) to solve pure LP
+problems using the interior point method (therefore the program
+GLPIPM was removed from the package).
+GLPK 2.3 (release date: Apr 09, 2001)
+New edition of the document "GLPK User's Guide" is included in
+the distribution. Now it describes all additional API routines
+which were recently added to the package.
+The MIP solver was fully re-programmed in order to improve its
+robustness and performance. In particular, a basis recovering
+procedure was implemented (this procedure allows switching to
+the primal simplex method in case when the dual simplex method
+fails).
+GLPK 2.2 (release date: Mar 15, 2001)
+Now GLPK includes a tentative implementation of the
+branch-and-bound procedure based on the dual simplex method for
+mixed integer linear programming (MIP).
+Complete description of this new feature of the package is given
+in the preliminary document "Mixed Integer Linear Programming
+Using GLPK Version 2.2 (Supplement to GLPK User's Guide)". This
+document is included into the distribution in plain text format
+(see the file 'mip.txt' in the subdirectory 'doc').
+The MIP solver (glp_integer) can be used as GLPK API routine in
+the same way as the pure LP solver (glp_simplex).
+The stand-alone program 'glpsol' is now able to solve LP as well
+as MIP problems.
+Note that the current version of GLPK MIP solver is based on
+easiest heuristics for branching and backtrackng. Therefore the
+solver is fit mainly for MIP problems which are not very hard
+and have few integer variables.
+GLPK 2.1 (release date: Feb 19, 2001)
+The document "GLPK Implementation of the Revised Simplex Method"
+is included into the distribution. This document describes most
+of routines related to the revised simplex method.
+GLPK 2.0 (release date: Jan 25, 2001)
+Now GLPK includes a tentative implementation of the primal-dual
+interior point method for large-scale linear programming.
+The interior point solver can be used as GLPK API routine in the
+same manner as the simplex method solver (glp_simplex):
+ret = glp_interior();
+Note that currently the interior point solver implemented in
+GLPK doesn't include many important features, in particular:
+* it can't process dense columns; therefore if the problem has
+dense columns, the solving will be extremely inefficient;
+* it has no special features against numerical unstability;
+some problems may cause premature termination of the solving
+when the matrix A*D*A' becomes ill-conditioned;
+* it computes only values of primal (auxiliary and structural)
+variables and doesn't compute values of dual variables (i.e.
+reduced costs) which are just set to zero;
+* it doesn't identify optimal basis corresponding to the found
+interior point solution; all variables in the found solution
+are just marked as basic variables.
+GLPK also includes a stand-alone program 'glpipm' which is a
+demo based on the interior point method. It may be used in the
+same way as the program 'glpsol' that is based on the simplex
+method.