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Updated for XPRESS 8.13, linked with libs version 39.01.02
MIP related: mipcomponents, mipconcurnodes, mipconcursolves, nodeprobingeffort, heuremphasis,
miprestart, miprestartgaptol, miprestart, miprestartfactor, autocutting
Algorithms: siftswitch, siftpasses, netstalllimit, barrefiter, barobjperturb
Others: prefolding, inputtol, maxstalltime
Added a value to deterministic to that allows a concurrent root LP solve to be opportunistic
Fixed possible problem in the licencing routines for computer with many MAC addresses.
Relinked with ASL version 20210613 to fix a fault with indicator constraints.
Relinked to use XPRESS 8.11.2. Patch for MacOS not available at the moment
of release as the solver library is not available.
xpress.c: now uses xpress API to get version string.
xpress.c: update to XPRESS 8.10, which has bug fixes and
improvements. New keywords: autoscaling, feastol_perturb.
New control bits for refineops. See the xpress -= output.
[MacOS] Added support for older version of MacOS.
xpress.c: relinked to eliminate bogus output when an AMPL license is not found
xpress.c: update to XPRESS 8.9, which has bug fixes and improvements.
xpress.c: update to XPRESS 8.8, which has bug fixes and
improvements. New keywords: globalfilemax, globalloginterval,
maxmemoryhard, mipdualreductions, resourcestrategy. Expanded
description of refineops. Keyword nodefilebias is now noted
as “deprecated and ignored”. See the “xpress -=” output.
xpress.c: update to XPRESS 8.6, which has bug fixes and
improvements. New keywords: barkernel, elimfillin, mipkappafreq,
objscalefactor, preconvertsep. See the “xpress -=” output.
xpress.c: when available (starting with XPRESS 8.5), use attribute
XPRESSVERSION to obtain the “8.5.10” in the current “AMPL/XPRESS
8.5.10(33.01.12)” part of the solve_message and “xpress -v” output.
Previously this had to specified with a -D option when compiling
xpress.c. Now changes to the XPRESS libraries in use should be
reflected in this string.
xpress.c, README.xpress: Adjust “maxtime” description (in
“xpress -=” output and in README.xpress) to accord with XPRESS
documentation. For n > 0, maxtime=n allows execution to run more than
n seconds if needed to obtain a first feasible solution, at least on
problems with integer variables.
Update to XPRESS 8.5, which has some bug fixes and improvements.
See the “xpress -=” output for more details.
Modified keyword (to be withdrawn):
xpress.c: adjust to allow solving problems with more than 2^31
nonzeros (on 64-bit systems).
xpress.c: add keyword bargaptarget; see the -= output for details.
xpress.c: update to XPRESS 8.4.
New keywords heurforcespecobj, lpfolding, preanalyticcenter and
prebasisred, and some new possible values (7,8,9) for tunertarget.
See the “xpress -= output”.
xpress.c: add keyword “writeprob”; see the “xpress -=” output for
README.xpress: update with current “xpress -=” output.
xpress.c: fix a glitch in the ordering of #include directives.
The glitch had no effect on binaries generated by AMPL Optimization
because of the way license checking is done.
Arrange for the solve_message to have the form “XPRESS xx.yy.zz”
rather than just “XPRESS.xx.yy”. With XPRESS 8.2 this is
“XPRESS.31.01.02” and with XPRESS 8.3 it is “XPRESS.31.01.09”.
Update for XPRESS 8.2. New keywords:
xpress.c: change erroneous want_deriv to want_derivs, which should
slightly reduce times to read problems involving quadratic expressions.
Suppress call on XPRSgetlpsol() when LPSTATUS is 7 (XPRS_LP_UNSOLVED),
so the solve exit code will be 0 rather than 1.
Add keyword “param”. See the “xpress -=” output for details.
Add keyword “barobjscale”.
Update for XPRESS 8.0. New keywords:
Update for XPRESS 7.9. New keywords:
New keyword “bestbound”. See the updated “xpress -=” output.
New keywords for MIP solution pool:
Updated description of “heurthreads”. For details, see the
“xpress -=” output or the updated README.xpress.
New keyword “advance”. Specifying advance=0 in $xpress_options
has the same effect as “option send_statuses 0;” before “solve;”
in an AMPL session.
Update for XPRESS 7.8. New keywords
Update for XPRESS 7.7. New keywords dualthreads, maxmemory,
prebndredcone, prebndredquad, prelindep, preobjcutdetect. See the
“xpress -=” output for details. Tested with libraries for which
“xpress -v” says “AMPL/XPRESS 26.01.04 …”.
When iis appears in $xpress_options and a linear problem is infeasible,
return an IIS in suffix .iis; if changing the bounds on just one
constraint or variable would remove the infeasibility, also return
suffix .iso with value 1 for each such constraint or variable.
Change calls on Sprintf to simpler, safer calls on Bpf. Should be
Fix a glitch (possible fault) with objrep.
Update for XPRESS 7.6. New keywords barcores, miqcpalg, qccuts,
qcrootalg. See the “xpress -=” output for details. Tested with
libraries for which “xpress -v” says “AMPL/XPRESS 25.01.05 …”.
Add keyword “lazy” for recognizing suffix .lazy, with nonzero values
indicating that linear constraints are “lazy” or “delayed” if the
problem has integer variables.
Add keyword “objrep” controlling whether to replace:
minimize obj: v;
minimize obj: f(x)
when variable v appears linearly in exactly one constraint of the form
s.t. c: v >= f(x);
s.t. c: v == f(x);
Default is no for the former, yes for the latter. For more details,
invoke “xpress -=”. This requires use of version >= 20130622 of the
AMPL/solver interface library.
Update for version 7.5. New keywords: baralg, barreg, treepresolve.
Add “network” keyword instructing xpress to identify and exploit
an embedded network.
Correct the description of “sos2” in the “-=” output.
Updates to README.xpress, makefile.u, makefile.vc and addition
of shell scripts xpress.linux and xpress.macosx.
Add keyword “version”, to report version details before solving
xpress.c: updates for XPRESS 23: new keywords cpuplatform,
preduprow, presolvemaxgrow, symmetry. The updated driver still
works with XPRESS 22.
xpress.c: add keyword mipstartvalue with synonym mipstart to
control whether a starting guess for a MIP problem is passed
to XPRESS. Hitherto a starting guess was ignored; now the
default is to use it, but specifying mipstartvalue=0 will cause
it not to be used. Also arrange for “xpress -v” to report the
version of XPRESS being used.
xpress.c: updates for XPRESS 22.
xpress.c: catch SIGINT (control-C) and return the best available
solution. Quickly giving several control-C’s may sometimes lead to
the new solve_result_num value 520 (and no returned solution).
README.xpress: minor adjustments.
xpress.c: increase constraint.sstatus array length by one to fix
a possible fault.
xpress.c: fix a bug in the update of 20110825.
xpress.c: add support for indicator constraints, i.e., logical
constraints of the form
s.t. foo: b == c ==> constraint1 [else constraint2]
with b a binary variable, c = 0 or 1, and the constraints simple
inequality or equality constraints. This requires linking with
version >= 20110913 of the AMPL/solver interface library.
xpress.c: some bug fixes, e.g., in handling quadratic forms,
supplied by David Nielsen.
xpress.c: fix a bug with quadratic constraints involving some
variables that only appear linearly.
xpress.c: omit the “debug” keyword unless compiled with -DRWA_DEBUG .
xpress.c, README.1st, README.xpress: update to version 7.1.