Xpress-Optimizer and Xpress-SLP patch 27.01.17 for Xpress 7.8

Document created by zsoltcsizmadia@fico.com on Apr 10, 2017
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Xpress-Optimizer and Xpress-SLP patch 27.01.17 for Xpress 7.8 is now available on the FTP and Box for Windows 64 and 32, Linux 64 and 32 from




Xpress-Optimizer release notes:


* Fixed an incorrect behavior of XPRSgetcols, XPRSgetcols64, XPRSgetrows, and XPRSgetrows64 that return wrong mstart[] if the requested number of nonzeroes is smaller than the number of coefficients in the requested columns/rows.

* Fixed an incorrect sign change in quadratic constraints with equality sign.

* Fixed an issue where an integer variable used in quadratic terms was erroneously converted to a binary variable.

* Fixed a rare issue related to solving a system of linear equations.

* Fixed an issue where parallel dual simplex method may wrongly declare a numerical unstable problem as unfinished.

* Fixed an issue where a rotated second order cone may be taken with wrong variable signs.

* Improved objective scaling in the barrier algorithm.

* Improved behavior of the homogeneous barrier algorithm.

* Fixed an issue where a super optimal solution was created after a restart.

* Fixed an issue with XPRSpresolverow that could result in the right-hand side for a presolved row being returned undefined.

* Fixed an issue where the declared the problem to be infeasble during the root node processing.

* Fixed an issue with node-to-node dual reductions for MIPs with indicator constraints that could cause optimal valid solutions to be dropped.

* Fixed an issue in the disconnected component presolver w.r.t. sub-optimal solutions

* Fixed an issue in the disconnected component presolver for problems with very large objective values that in rare cases could result in the problem being declared infeasible.


Xpress-Nonlinear release notes:


* Fixed a problem related to numerical derivatives over fixed variables when presolve is disabled.


This is the latest Xpress-Optimizer and Xpress-SLP patch for the Xpress 7.8 release branch. Please note that it must be installed over a prior installation of FICO Xpress 7.8 and requires a valid Xpress 7.8 license.