HiGHS Changelog

20230531

  • MIP start. HiGHS 1.5 supports complete MIP starts only. For partial MIP start, user solve with fixed known variables first (Modeling Tip #7).

  • Wrong solver options are gracefully reported via solve_message.

20230522

  • Fixed solution status reporting to AMPL

  • Fixed basis input with obj offset or missing data

  • Added warm start for LP problems

  • Reading column names from col file is present

20230424

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

20230227

  • Fixed a problem when retrieving basis status

  • Implemented retrieval of MIP gap so that if optimality is reached via presolving, the returned gap is 0

20230224

  • Updated to HiGHS 1.5.1; now returning number of LP iterations in a MIP solve

20230222

  • Fixed: now returning the correct dual values for the constraints

20230209

  • Updated to HiGHS 1.4.2

  • Fix for error encountered when passing variables status if variables with unknown basis status are present.

20230207

  • Changes in the MP library

20221228

  • Changes in MP

20221222

  • Updates for HiGHS 1.4.1

    • The run_crossover option has now values “on”, “off” and “choose”. The latter results in crossover being run if the result of IPM without crossover is imprecise

    • Bug fixes

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.

20221012

  • Piecewise-linear approximation of quadratics HiGHS accepts quadratic objectives. For nonconvex ones, set cvt:quadobj=0. Recognizing x^2 for stronger univariate approximation

20220928

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

20220603

  • Fixed an issue with passing/retrieving basis information

20220524

  • First release of HiGHS for AMPL