When primal infeasiblity is detected in presolve, no dual ray is available so, previously, the has_dual_ray parameter of Highs::getDualRay returned false and that was it. Now, if a null pointer is not passed for dual_ray_value, Highs::getDualRay will compute a dual ray - at the cost of solving the feasiblility LP without presolve. The same is now true for Highs::getPrimalRay. Highs::getDualUnboundednessDirection has been introduced to determine the product between the constraint matrix and the dual ray, forcing the calculation of the latter if necessary. Once a dual ray is known for the incumbent model in HiGHS, subsequent calls to Highs::getDualRay and Highs::getDualUnboundednessDirection will be vastly cheaper
The method Highs::getDualObjectiveValue now exitsts to compute the dual objective value, returning HighsStatus::kError if it is not possible.
The method Highs::getStandardFormLp now exists to return the incumbent LP in standard form - overlooking any integrality or Hessian. To determine the sizes of the vectors of data, the method is called without specifying pointers to the data arrays.
Added documentation on the use of presolve when solving an incumbent model, and clarifying the use of the method Highs::presolve.
HiGHS will now read a MIPLIB solution file
Added time limit check to HPresolve::strengthenInequalities
Added getColIntegrality to highspy
Now computing the primal-dual integral, reporting it, and making it available as HighsInfo::primal_dual_integral
Trivial primal heuristics "all zero", "all lower bound", "all upper bound", and "lock point" added to the MIP solver