COPT Changelog

20240410

• Updated to Copt 7.1.1, with support for first-order method (PDLP). On Windows this can be used with GPU supporting CUDA. It can be controlled setting lp:method to the new value 6 (PDLP) and with options lp:pdlpgpumode, lp:pdlpgpudevice and lp:pdlptol

20240320

• SOS constraints.

  • Fixed handling of SOS2 constraints created by AMPL as reformulations of PL expressions (option pl_linearize 1, default; set to 0 to use MP linearization.)

  • Disallow repeated weights for SOS constraints (suffixes .sosno/.ref.)

• Option report_times

• Unused acc: options.

  • The constraint acceptance options acc:... for non-handled constraints are ignored (previously triggered error.)

20240115

• Solve result codes.

  • List codes by running (solver) -!

  • [BREAKING] Standardized codes. Major changes:

    • 100-199 (solved?) means solution candidate provided, but can be suboptimal/infeasible

    • 300-349 means unbounded problem but feasible solution returned

    • 400-449 means limit/interrupt but feasible

  • [BREAKING] sol:chk:fail returns code 150 (solved?)

• Improved translation of SOCP constraints.

  • Options cvt:socp, cvt:socp2qc.

• Compact solution check warnings

• Fixed presolve of the power function #226.

20231117

• Updated to Copt 7.0.3, which includes many performance improvements

• New keyword lim:soltime to specify a time limit after a solution has been found

• MP update: fixed graceful exit on Ctrl-C from AMPL in Linux and fixed issue with reading text-format NL files

20231103

• Improved translation of logical constraints: inlining of nested disjunctions and conjunctions; fewer auxiliary binary variables.

20231017

• Fixed a bug in NL reader on Windows.

20230919

• mp_options. Receive mp_options from AMPL (for all MP solvers). They are parsed before (solvername)_options.

• Solution checking: relative tolerance sol:chk:feastolrel; options sol:chk:round, sol:chk:prec.

20230831

• Solution checking, options sol:chk:* (experimental).

• Preprocess And/Or constraints.

20230817

• Alternative solutions: solve status equal to that of the final solution.

• Fixed a bug causing repeated names for auxiliary variables and constraints.

• Option values can be assigned without ‘=’.

• Fixed a bug where equivalent conditional comparisons were not unified.

20230726

• Fixed inequalities of integer expressions with non-integer constants, see test_int_non_int.mod.

20230724

• Option [solver_]auxfiles rc; transfers names of variables and linear constraints into the model; (solver)_options ‘cvt:names=0-3’ controls names.

20230621

• Fix quadratic objective with repeated subexpressions.

20230616

• Changes in MP.

20230428

• Updated to Copt 6.5.2, which includes performance improvements and fixes for issues with MIP problems

20230424

• Changes in the MP library: added variable names support and removed spurious starting solution

20230330

• Recognition of second-order conic constraints from algebraic representations and conversion into quadratic constraints; COPT appears to recognize second-order cones from quadratics.

20230207

• Changes in the MP library

• Updated to Copt 6.0.4, which includes bugfixes

• Added support for unbounded/Farkas rays calculation

20221228

• Changes in MP

20221222

• Bug fixes in MP

20221211

• Changes in MP: added the ==> else operator Implemented implication with ‘else’: constr1 ==> constr2 [else constr3]

• Changes in MP: PLApproxRelTol, PLApproxDomain Parameters to control piecewise-linear approximation. cvt:plapprox:reltol default value changed from 1e-5 to 0.01.

20230207

• Updated to Copt 6.0.1, which includes: many performance improvements native support for quadratic constraints

20221012

• Piecewise-linear approximation of quadratics For non-convex quadratics, set the following options: cvt:quadobj=0 and/or cvt:quadcon=0.

20220928

• Changes in MP: piecewise-linear approximations of nonlinear functions, default value of big-M

20220715

• Updated to Copt 5.0.1, which includes many performance improvements

• Added feasibility relaxation (see alg:feasrelax)

• New parameters: alg:iismethod

20220615

• New parameter: crossover

• Minor changes to parmeter names

20220526

• SOS constraints are now detected also if the .ref suffix is integer

• Minor changes to parmeter names

20220511

• Complementarity constraints: also quadratics Complementarity constraints now handle quadratics.

• Branch develop is used for new code The active development branch is now develop.

• Convert quadratic range constraints to QuadCon(LE/EQ/GE) COPT does not support quadratic range constraints. Conversion of linear range constraints into one-side rhs constraints has been generalized for any algebraic ones.

20220411

• First mp-based release, linked with COPT libraries 4.0.5

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