CPLEX Changelog#

20241206#

Options primalopt, dualopt, baropt, siftopt, netopt, bendersopt are now flags (e.g. they have to be set without a value)

CPLEX MP driver is now the default. To use the previous ASL-based driver set: option solver cplexasl;
Added many options available in the ASL driver
Notable changes with ASL driver:
- Keyword ‘basis_cond’ is now ‘kappa’ and follows the standard MP implementation
- Multiobjective optimization follows the MP standard implementation
- Choosing solution algorithm for the LP problems or the initial MIP subproblem (formerly mipstartalg) now follows the same standard as other MP drivers: see alg:method in the -= output
- Former option timing is now implemented through the corresponding MP feature. To print the number of available cores use tech:numcores.
- Use MP feature tech:writemodelonly instead of writeprob + nosolve. Note that nosolve still applies when specifying writemipstart
Conversion of basis status for constraints depending on sense

Option acc:_all
- Useful to disable all reformulations (acc:_all=2), or force linearization (acc:_all=0).
Option cvt:prod
- Controls reformulation of binary products into logical constraints.
Faster input of quadratic expressions.

Multi-objective emulator
- obj:multi=2 forces emulation, even if MO natively supported.
- Fixed a bug in the objective degradation suffixes .objasbtol, .objreltol.

Multi-objective emulator
- All flat MP solvers support multi-objective mode (obj:multi=1), either natively, or via emulation.
- Suffixes .objpriority, .objweight, .objabstol, .objreltol.
- [BREAKING] Default intuitive handling of .objweight, see option obj:multi:weight, even when natively supported.

[BREAKING] Merged report_times and timing; they are now aliases, set the value to 1 to have basic info, to 2 to have more detailed info.

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 the solver’s native PL functions or 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.)

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.
Added fixed model for mip:basis
Added options:
- alg:method and flags to choose the solution algorithm
- mip:nodemethod to choose the algorithm used for MIP node problems
- lp:solutiontype to choose if to use crossover to get a basis basis solution after barrier

Public beta; implemented most features in MP: model export, warm start, input and output basis, feasibility relaxation, multiple solutions, kappa, unbounded rays, IIS, return MIP gap, return dual bound
Native Model support:
- continuous and integer variables
- multiple objectives, quadratic objectives
- linear and quadratic constraints, indicator constraints and PL functions
- special ordered sets (type 1 and 2)

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