Xpress Update 9.4.6

Community Manager

6 months ago

Xpress Updates 9.4.6 is now available on the client area for Windows, Linux, and MacOS on x86-64, and Linux and MacOS on AArch64, from
https://clientarea.xpress.fico.com/download_patch.php#946
This is the latest updates for the Xpress 9.4 release branch, respectively, and require matching licenses. Please note that these archives must be extracted over a prior installation of FICO Xpress 9.4, respectively.

Release Notes for 9.4.6
Xpress Optimizer 43.01.07

Fixed an issue with disconnected component solves that could result in a sub-optimal solution being returned.
Ensure minimum tolerance on GCDs is respected.
Fixed a performance bottleneck in linearization of equality indicators during presolve.
Fixed an issue with disconnected component solves for MIPs that could result in delayed rows being violated.
Fixed an issue in the Lifted GUB cover cuts separator, which could result in a crash in some rare cases.
Fixed an issue in the Strong Chvatal-Gomory cuts separator, which in rare cases could result in the separation of non-valid cuttig planes on some numerically challenging models.
Fixed an issue that could lead to a crash when solving a mixed-integer quadratically constrained problem after solving a quadratic problem.
Improved the infeasibility detection in the primal simplex algorithm.
Fixed a potential crash when running repairinfeas on a problem with no rows.
Fixed an issue with IIS returning the wrong status for a feasible MIP.
Significantly reduced initialization overhead for lpoptimize/mipoptimize, in particular when OUTPUTLOG is set to XPRS_OUTPUTLOG_NO_OUTPUT.
Fixed a problem where calling XPRSsetdefaults reset the problem name.
Fixed a potential crash during presolve when converting quadratic rows into second-order cones.
Fixed an issue in quadratic presolve deriving invalid variable bounds.
Fixed an issue with the community license, that could cause the optimizer to take a different solution path with respect to the path taken when used with a full license.
Fixed an issue in presolve where in some edge cases incorrect fixings could be produced from quadratic or indicator rows.
Fixed the problem detection for tuning with multiple instance to correctly distinguish LP and MIP problem sets.
Fixed an issue where primal simplex could return a slightly infeasible solution.

Xpress Nonlinear 43.01.07

Avoid stackoverflow for deeply nested formulas.
Fixed a crash when calling XPRSoptimize for a nonlinear problem with the flags argument being NULL.
Fixed a potential crash for userfunctions providing derivatives.
Fixed an issue with userfunctions returning derivatives when some of the input arguments of the user function in the formula were constant.

Xpress Global 43.01.07

Fixed an issue with domain propagation of the power function that could result in feasible solutions being dropped.
Fixed an issue related to setting CALLBACKFROMMAINTHREAD=1 for global solves.

Xpress Interfaces 43.01.07 (Python, R, Matlab, .NET, Java, C++, C)

Python
- Fixed a crash when calling extractLinear() on an empty expression.
- problem.getnamelist() now supports all object types.
- Model properties on variable, constraint and sos objects, such as var.lb, are no longer accessible from callbacks or while the problem is presolved. Properties of the presolved problem can be queried using functions such as problem.getLB() instead.
- Fixed a crash when accessing Xpress NonLinear controls and attributes from callbacks.
- Fixed a crash when converting Python expressions to nonlinear formulas with more than 512 tokens.
- Fixed a crash when passing iterators of more than 512 elements to API functions.
R:
- Fixed interface compatibility with R version 4.5.0 and above.
Java, C#
- Fixed scope of solution pool objects in some examples.