Xpress Update 8.4.7

Document created by Michael.Perr on Apr 6, 2018
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Xpress Update 8.4.7 is now available on Box.com for Windows, Linux and Mac, from




This is the latest update for the Xpress 8.4 release branch. Please note that it must be installed over a prior installation of FICO Xpress 8.4 and requires a valid Xpress 8.4 license.


Release Notes:


Xpress Optimizer 32.01.10:


  • Fixed an issue that could result in an infeasible solution from the barrier algorithm.
  • Fixed an issue that might trigger a failure in the Dot product of the Python interface when handling nonlinear expressions.
  • The Sum and Prod methods of the Python interface now accept None as its neutral element.
  • Fixed a potential deadlock when Mosel callbacks are used to add cuts in parallel MIP solves
  • Fixed some issues in the Python interface in the way it handles controls and attributes, parameters to callbacks, and various API functions.
  • Fixed issue with xpress.problem.storecuts() in the Python interface.
  • Fixed some issues in the dot product implementation of the Python interface that may affect its result.
  • Fixed a performance issue with long reoptimization loops in diving heuristics.
  • Fixed issue when calling XPRSgetdualray and a factorization is not present.
  • Relaxed some tolerances around user solutions, to prevent minor numerical issues from causing solutions to be rejected.
  • Setting PREBASISRED=1 will now ignore density checks when deciding whether to apply basis reduction.


Xpress Nonlinear 32.01.10:


  • * XSLP_STATUS will now have XSLP_STATUS_INTEGERINFEASIBLE set if the SLP-MIP-SLP method is infeasible in the MIP search.
  • * XSLP_STATUS will now have XSLP_STATUS_ENFORCED set if XSLP_MAXERRORCOST is hit and all error variables are removed.
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