(maintain each list from top to bottom)


16 Oct 2013 - Release 1.7.2
===========================

fixed bugs:
- fixed minor bug in SVSet::add()
- restore slack basis if a basis with too many or too few basic entries is loaded
- higher precison when writing .lp or .mps files, similar to SCIP standards


04 Jan 2013 - Release 1.7.1
===========================

code quality & new features:
- unfied members/methods of CLUFactor in new file clufactor.cpp (contains factor.cpp, forest.cpp, update.cpp, (v)solve.cpp)
- moved code from message.h,cpp to spxdefines.h,cpp to avoid name clashes with SCIP

fixed bugs:
- fixed inconsistent generic column and row names
- fixed bug in adjusting basis statuses to sides/bounds when loading or reloading the basis
- fixed bug in refactorization in the case when update detects singularity: invalidate only the factorization, not the
  matrix since this would change the order of colums/rows in the basis
- catch possible exception when finally performing basis update
- fixed inconsistency in "Fast" ratiotester when "short" leave is possible
- fixed bugs in unsimplification of zero objective singleton columns and row singletons
- relaxed wrong assert in SPxSolver::unShift()
- fixed bug in ratio test: consider only nonbasic entering variables in leaving algorithm, also in row representation
- reverted wrong bugfix (99f913d7) in computeLeaveCoPrhs4Col() for column status D_UNDEFINED

interface:
- new methods in SPxSolver to set and get maximum number of updates before next refactorization
- implemented writing of basis file for row representation
- implemented Farkas ray (for infeasible LPs) and primal ray (for unbounded LPs) for row representation


31 Jul 2012 - Release 1.7.0
===========================

code quality & new features:
- partial pricing can be switched on for dantzig-, devex- and steep-pricing by defining PARTIAL_PRICING (only LEAVING mode)
- current basis matrix can be written to a file in MatrixMarket format using SPxBasis::printMatrixMTX
- exact initialization of steepest edge weights possible by calling setupWeights of SPxSteepPR
- option -bw writes the basis of the original problem to a file; works now with simplifier as well
- allowed primal and dual feasibility tolerance to be set independently in simplifier and simplex routines
- added GMP support and data type MpqReal, a wrapper for mpq_class if compiled with GMP=true, soplex::Real otherwise
- implemented iterative refinement for feasible and bounded LPs, applied when a feasibility or optimality tolerance below
  the new parameter SPxSolver::irthreshold() is requested
- reduced and commented code by adding "void deleteVec(DLPSV* ps);" method in svset.{h,cpp}

fixed bugs:
- variables that do not appear in the objective function or any constraint are not printed anymore in the BOUNDS section
  of the mps file
- allow instable leave iterations, i.e., leave iterations with pivot element below default stability threshold, only
  after a fresh factorization
- check redundant variable bounds implied by rows more carefully: do not apply if max/min activity exceeds sides by a
  factor greater than 1.0/epsilon to avoid roundoff errors
- initialize basis descriptor to statuses D_UNDEFINED in order to avoid access of uninitialized values at time out
- fixed bug in stalling detection: SoPlex incorrectly assumed that pricing had been finished and hence claimed optimality
- handled setting FIXED basis status when bounds are only approximately equal
- using a starting basis from file disables simplifier
- fixed bug in computeLeaveCoPrhs4Col() for column status D_UNDEFINED
- fixed bug in unsimplifying singleton rows
- fixed cycling caused by refactorization after pricer finds no more candidates
- fixed bug that bound changes were not performed if new bound deviates by only epsilon; this can lead to slightly
  inconsistent bounds which trigger asserts later
- sparse pricing stores only infeasibilities > entertol() in leaving or > leavetol() in entering (was epsilon() before)
- fixed false infeasibility detection in ratiotest after fresh factorization
- fixed bug in the svset data array, when removing the first vector, the memory was not 'freed' and therefore the memory
  consumption could have increased to a very huge value (bug 319)
- also fixed wrong ensureMem() call in SVSet create(), which lead to a to big data array and change an unnecessary
  insert() call to an reSize() call
- corrected a memcpy() to a memmove() call due to possible overlapping memory
- fixed bug in counting unsuccessful pivots

interface:
- info message in case a fresh factorization is not stable enough and has to be done again with higher Markowitz threshold
- new command line option -p6 to use steepest edge pricer with exact initialization
- verb levels v4 and higher display current pricing mode (sparse or conventional)
- additional simplify() method with independent primal and dual feasibility tolerance as parameters
- new exception SPxInterfaceException to be thrown if inconsistent parameters are passed to interface methods
- new methods feastol(), opttol(), setFeastol(), setOpttol() in classes SoPlex and SPxSolver to get/set primal and dual
  feasibility tolerance; delta() and setDelta() still exist and work as before
- new command line options -f and -o to set primal feasibility and optimality tolerance, respectively; -d still exists and
  works as before
- exact steepest edge is the new default pricing strategy and is implemented as separate class (inherited from SPxSteepPR)
- correct dual statuses when loading a basis with SPxBasis::loadDesc(); they might have become inconsistent when bounds
  or sides had been changed
- new methods SPxLP::computePrimalActivity() and SPxLP::computeDualActivity() for given primal and dual solution vectors
  using exact arithmetic
- new methods irthreshold() and setIrthreshold() for threshold parameter below which iterative refinement is applied
- new command line option -R to set parameter irthreshold()

performance:
- sparse pricing for leaving and entering simplex is activated depending on ratio of basis dimension and number of infeasibilities
- fixed performance issue removing (all) vectors from a SVSet where it is better to delete the elements from behind to
  the front


28 Oct 2011 - Release 1.6.0
===========================

code quality & new features:
- time for basis updates can now be measured by defining flag MEASUREUPDATETIME in spxbasis.h (off by default)
- removed "-static" option from Makefile due to linking troubles on newer systems without static libraries; can still be
  added using the make option "USRLDFLAGS=-static"
- added -fp:precise and -Oi to make.mingw.x86.{cl,intel}.opt
- added define SOPLEX_SUBVERSION to track internal development version (src/spxdefines.h)
- added SHARED variable in Makefile for creating shared libraries and binaries
- added functionality to solve systems with three right hand sides
- added partial quicksort to sorter.h
- increased priority of debugging output
- added "install" target to Makefile; this target can be used to install SoPlex into certain directory on the system
  (works for Linux and Mac); for this, you have to specify INSTALLDIR (make install INSTALLDIR=/urs/local/)
- removed compiler flag NO_ADDITIONAL_CHECKS in code and makefile options: now, additional checks are only performed
  when ENABLE_ADDITIONAL_CHECKS or ENABLE_CONSISTENCY_CHECKS is explicitly defined (globally or in a specific file)
- githash of current commit is displayed (also in check mode)

interface:
- LP reader: print warning when encountering a floating point number with empty exponent (hints at variable name with
  initial 'e' or 'E')
- methods selectEnter() and selectLeave() in ratio testers now receive index/id of leaving/entering variable as input
  parameter
- added methods to solve the linear systems of equations for 3 right hand sides simultaneously
- added method getPrimalray() to classes SoPlex and SPxSolver for primal unbounded LPs
- added command line option '-L' to set iteration limit
- allowed free basis status (SPxSolver::ZERO, SPxBasis::Desc::P_FREE) for variables and constraints with finite bounds
- adapted method to read/write basis for free nonbasic variables
- added command line option '-t3' to use the bound flipping ratio test (long step dual)
- number of performed bound flips during ratio test are displayed as 'flips=' in line 'Finished solving...'
- added method to clear starting basis in class SoPlex (SoPlex::clearBasis())

performance:
- increased default Markowitz threshold to 0.04 to increase numerical stability of the factorization
- implemented bound flipping ratio test ("long step dual") for column representation

fixed bugs:
- added missing -m64 in LDFLAGS of make.{darwin,sunos}.x86_64.gnu.* and make.{linux,freebsd}.x86_64.gnu.opt*
- added missing -DNDEBUG in make.mingw.x86.{cl,intel}.opt
- fixed incorrect access to member variables in constructors of class DataHashTable
- fixed bug in SPxFastRT: also in the first phase consider only nonbasic entering variables in COLUMN/LEAVING mode
- fixed bug in COLUMN/ENTERING algorithm yielding incorrect detection of unboundedness or inverted primal ray: when
  deciding whether a free variable entering the basis should increase or decrease from zero, we have to look at the
  reduced cost, not the objective function
- fixed too early check of iteration limit (now not checked in SPxSolver::terminate() anymore, but at beginning of each
  iteration)
- fixed bug in unsimplifcation of duplicate rows presolving
- fixed bug when setting basis through class SoPlex
- fixed bug occuring with large column/row bounds: if we refactorize, we also have to recompute the right hand side of
  Bx=b, because roundoff errors might have occured during its update
- fixed segmentation fault in simplifier when postsolving is interrupted with an exception
- fixed wrong error output in statistics when an instance is solved during presolve
- pricer SPxDevex now performs one additional pivot if only slightly feasible/optimal; this helps to prevent suboptimal
  results on some unsimplified instances
- fixed potential NULL pointer dereference in nameset.h, when name is not found in hashtable
- fixed potential segmentation fault when calling sorting routines on empty arrays (sorter.h)
- send debugging output to standard out instead of error stream
- fixed bug in unsimplification of duplicate columns (do not replace two linearly dependent columns by one if free basis
  status can not be resolved in unsimplification)
- fixed several bugs when unsimplifying infeasible bases
- fixed counting of removed rows during simplifier


30 Sep 2010 - Release 1.5.0
===========================

code quality & new features:
- changed memory handling in class DataKey: replacing bitfield implementation by two int's
- improved handling of singular bases and cycling: automatically restart from initial basis with tighter tolerances
- major rework of simplifier SPxMainSM: "localized" postsolving steps; several bugfixes concerning basis statuses, dual
  values and reduced costs
- performance improved in simplifier SPxMainSM: always processing singleton rows before finding duplicate rows; ignoring
  singleton rows and columns when checking for linear dependency

interface:
- submakefile for FreeBSD added
- added command line option '-y' to output dual row multipliers
- additional interface method SoPlex::setBasis to set starting basis if no simplifer present

fixed bugs:
- bug in class SoPlex appearing when LP is solved completely in simplifier and optimal solution retrieved
- bug in spxbasis.cpp: when basis is detected as singular during update step, now we refactorize to double check; if the
  singularity is not resolved we exit with correct status
- bug in simplifier postsolving: empty columns may not only be fixed to bounds but also to zero for free variable
- bug in SPxSolver::setPricer() appearing when switching pricers in initialized state
- bug in simplifier SPxMainSM yielding incorrect dual values and reduced costs for maximization problems
- bug in simplifier SPxMainSM for postsolving of free columns with zero objective
- bug in factorization triggered by column singletons with nonzeros below numerical zero tolerance


11 Sep 2009 - Release 1.4.2
===========================

code quality & new features:
- in class SoPlex, enabled getBasis... methods also when simplifier is present and basis suboptimal, but regular
- added check for stalling in main solve loop SPxSolver::solve(): if objective value and shift haven't changed after a
  large number of iterations, switch algorithm; this fixes a timeout of SCIP/SoPlex on instance glass4 (MIPLIB2003)

interface:
- small change in spxmpswrite.cpp: always write the default upper bound of 1.0 for integer variables, since CPLEX seems
  to set infinity otherwise
- added method 'std::string statistics() const' to classes SoPlex, SPxSolver, SPxBasis, SLinSolver, SLUFactor, returning
  statistical information like number of factorizations etc.
- added method 'Real cumulativeTime() const' to class SPxSolver returning time used in all calls to method solve() since
  beginning or last call of 'resetCumulativeTime()'
- implemented copy constructors and assignment operators for almost all classes, especially SoPlex and SPxSolver
- the set methods (for pricer, ratiotester, ...) in classes SoPlex and SPxSolver now have an optional boolean parameter
  (false by default) controlling whether the memory of the object handed over shall be managed internally; this does not
  affect the default behaviour of the interface methods
- the constructor of class SPxSolver does not have parameters for pricer, ratiotester and starter, anymore; use the set
  methods instead

fixed bugs:
- now correctly resetting basis status to REGULAR in method SPxSolver::loadBasis()
- memory bug in function memPack() in svset.cpp; this method is now called to clean up memory, in case too much memory
  is wasted; this removes a large increase of the use of memory as tested in tests/testMemory.cpp
- bug in formulas for triggering refactorizations after increased relative/absolute fill
- memory leak in class SPxMainSM when calling simplify() multiple times
- bug in class DataKey leading to a segmentation fault when reading LPs with more than 8,388,607 variables or
  constraints: now the maximum number allowed is 536,870,911 and asserted in debug mode
- numerical bug in SPxFastRT leading to failed assert 'rep() == ROW' (in leave.cpp): in column/leaving algorithm, now we
  only consider nonbasic variables for entering the basis


20 Feb 2009 - Release 1.4.1
===========================

code quality & new features:
- speed up of the simplifier due to combined removal of rows/columns and combined updates of lhs and rhs in some cases
- overworked spxfastrt.h, spxfastrt.cpp
- added method isDescValid() in class SPxBasis to check if a descriptor is valid w.r.t. to the bounds of the loaded LP;
  use this to check whether previous/given basis can be loaded in SoPlex::solve()

interface:
- small changes in spxlpfwrite.cpp: make bounds LP-format conform, output 'generals' only if integer variables present
- added new method writeState() to classes SoPlex and SPxSolver for dumping LP, basis, and parameter settings at once

fixed bugs:
- bug in simplifier spxmainsm.cpp: wrong init for postsolving free column singletons fixed
- wrong bugfix in spxsolver.cpp:maxInfeas(): the leave and entering case were switched back
- endless loop triggered by different values of feasibility/optimality tolerance for pricer in spxsolve.cpp
- memory handling in class UnitVector
- bug when resolving in SoPlex::solve() after change of LP


30 Sep 2008 - Release 1.4.0
===========================

code quality & new features:
- split the main() method in example.cpp into several smaller methods
- created directory 'tests' that should contain small programs that illustrate a (former) bug in SoPlex or something
  like unit tests
- added member function precision() in spxout.h
- changed main target to soplexmain (from example)
- soplexmain.cpp now contains the main function, the output of this function should be more readable than the one of
  example; original output can be turned on with the "-C" command line argument, the example is now available as target
  'example' in the makefile
- name unification:
  + moved SPxLP::readFile() from spxfileio.cpp to spxio.cpp
  + renamed SPxLP::dumpFile() to SPxLP::writeFile(), included default params, moved it from spxlpfwrite.cpp to spxio.cpp
- simplified postsolving in spxmainsm.cpp (do not recompute reduced costs)
- overworked spxbasis.cpp:readBasis(): fixed bug and removed superflous code at end
- added fixing of the basis status if ZERO/P_FREE is not appropriate anymore, see varStatusToBasisStatusCol() and
  varStatusToBasisStatusRow() in spxsolver.cpp
- removed superfluous variable 'count' in spxparmultpr.cpp/h
- modifications in the simplifier SPxMainSM to avoid numerical problems
- modified reading and writing of basis: the row and column names are now passed as pointers; default names are
  entered if the pointers are 0; the changes appear in soplexmain.cpp, spxbasis.cpp, soplex.cpp, soplex.h

interface:
- introduced exceptions for all unrecoverable errors (lack of memory, no pricer, singular basis, etc.) to allow a
  calling application to clean up
- command line options "-V" and "-h" of example solver now output info on compilation flags
- replaced SPxLP::operator<< by SPxLP::writeLPF()
- implemented basic handling of reading a basis file (not yet thoroughly tested); the basic changes are in example.cpp,
  spxbasis.cpp, soplex.cpp, soplex.h
- added option to produce shared libraries with x86-Linux (OPT=opt-shared)
- constructor interface for the scalers SPxEquiliSC and SPxGeometSC changed: parameter colFirst is removed since the
  corresponding member is not used; printed names of the scalars are slightly changed; there are only 5 command line
  options for the scalar left since two of the previous 6 options coincided

fixed bugs:
- two bugs in spxlpfread.cpp: variables appearing in the bounds and general/integer/binary section
- bug in changeElement(): it now works also in the initial phase (NO_PROBLEM); aA corresponding test file is
  'tests/testChangeElement.cpp'
- bug in forest.cpp: use proper array access instead of pointer iteration
- bug concerning the termination value (objective limit) in spxsolve.cpp
- memory leak in postsolving of spxmainsm.cpp
- bug in spxchangebasis.cpp, addedRows(), addedCols(): need to call loadMatrixVecs in all cases, since the references to
  the matrix might have been invalided due to reallocation
- bug with detecting infeasible instances if scaling theCoTest does not help
- bug in spxlpfread.cpp with bounds on binary (old bounds were discarded)
- bug in spxsolver.cpp:maxInfeas(): the leave and entering case were switched
- bug in SLUFactor::solveRight4update(): now variable n is storing ssvec's size correctly
- bug in leave.cpp, left over from previous correction dealing with infeasible instances


27 Aug 2007 - Release 1.3.2
===========================

interface:
- keyword RANGES added in MPS format output (spxmpswrite.cpp)
- extended FAQ

fixed bugs:
- bug in spxmainsm.cpp concerning index mapping
- bug in unsimplify() if the problem has vanished in preprocessing
- missing check for singular basis at the end of factorize() in spxsolver.cpp
- assertion bug in FreeZeroObjVariablePS::execute() of spxmainsm.cpp
- bug in SVector::dim(): has to return the dimension and not the maximal index


21 Sep 2006 - Release 1.3.1
===========================

code quality & new features:
- made writeBasis() and writeBasisFile() in SoPlex and SPxSolver const-methods
- added SPxLP::writeLPF() with some parameters to dump an LP in .lp-format with variable and row names; this also fixes
  some output bugs; the still existing SPxLP::operator<< uses self-created default names
- check for necessary rounding added to spxmainsm

interface:
- restructured example.cpp and added a small example on constructing an LP using the callable library methods

fixed bugs:
- bug in spxmainsm: IDs of rows and columns are not used anymore
- bug in spxmainsm in connection with free variables
- bug in soplex method unsimplify(): check whether problem vanished in preprocessing added
- bug in spxlpfreader in connection with strange input (unconstrained rows)
- bug in ssvector: use ssvec.size() instead of b.size() (the former may be smaller due to flattened near-zero values)


03 Feb 2006 - Release 1.3.0
===========================

code quality & new features:
- a lot of stuff we have already forgotten about
- new preprocessing
- the number of warnings issued for ignored entries in MPS files is now limited to 1000 per file
- improved stability of textbook ratio tester
- added reference solution files for further LP suites
- extensive testing: coverage analysis and valgrind; new binary "exercise_LP_changes" performs kind of unit tests for LP
  change interface
- some assertions may be converted to generate warnings if NDEBUG is given; compile with "-DWITH_WARNINGS" to achieve this
- revised the whole documentation and made it doxygen-compatible
- made one-argument constructors explicit, added virtual destructors, blocked copy constructors and assignment operators
- rewrote major parts of ssvector.cpp to avoid pointer arithmetic
- added the spxout class to redirect output depending on the error level, provided all messages with a unique code for
  finding it with grep
- improvement of the LPF and MPS readers
- dropped all unused functions from the SLinSolver interface

interface:
- status output is now human-readable
- methods obj(), rhs(), lhs(), upper(), lower(), maxObj() of SPxLP that returned a non const reference renamed to *_w and
  made protected; use changeXXX() methods outside the class
- methods nofCols(), nofRows(), nofNZEs() deleted; use nCols(), nRows(), nNzos() instead
- methods obj(), rhs(), lhs(), upper(), lower(), maxObj() of LPColSet and LPRowSet that returned a non const reference
  renamed to *_w
- LPColSet: renamed obj() methods to maxObj()/maxObj_w(), renamed writable lower(), upper() methods to
  lower_w()/upper_w(), removed SPxLP::obj()
- LPRowSet: renamed writable lhs()/rhs() methods to lhs_w()/rhs_w()
- SPxSolver has got an additional NOT_INIT (not properly initialized) status
- renamed SPxDefaultPR to SPxDantzigPR

fixed bugs:
- bug in SPxSumST
- bug in memory allocation of SVSet: now uses doubling strategy correctly; the bug led to serious performance
  degradation on large LPs under Windows, which is now fixed
- some bugs in LP change interface
- segmentation fault in Forrest-Tomlin update
- bug in SSVector where zero vectors were not handled properly
- bug in example.cpp which resulting in ignoring the update type switch


10 Apr 2002 - Release 1.2.1
===========================

- interface of SoPlex::terminate() changed
- SoPlex::setRep(int) changed to SoPlex::setRep(Representation)


16 Jan 2002 - Release 1.2.0
===========================

(empty)
