v1.7.1

Version 1.7.1 of HiGHS contains several updates

Build changes

HiGHS on nixpkgs

HiGHS now has a flake.nix to build the binary, allowing nix users to try it out.

Python build update

On PyPI, highspy is now available as v1.7.1, bringing the Python and C++ versions of HiGHS into line.

Windows versions

Fixed version info of shared library
Added version info to executable

Code changes

Inserting pdlp_iteration_count into the struct HighsCallbackDataOut (for v1.7.0) breaks the C API, so it has been moved to the end of the struct, and an accessor function Highs_getCallbackDataOutItem has been added.

References to the compilation date have been removed from the build and code of HiGHS, so that binaries for the same version compiled on different days are identical. Methods to print compilation dates are deprecated.

setBasis has been added to highspy.

writePresolvedModel has been added, allowing the presolved model to be exported as a file.

The saved MIP solution pool is now populated with the optimal solution when presolve reduces a MIP to empty.

There is now a logging message and error return when a user-supplied solution or basis is rejected due to the size of any vector being incompatible with the dimensions of the incumbent model.

Memory allocation errors in presolve are caught and Highs::run() returns HighsStatus::kError with model_status_ = HighsModelStatus::kMemoryLimit.

QP solver logging is now neater and quieter.

Any Hessian for the incumbent model is modified with zero entries when adding columns to the model, and rows/columns are removed when columns are deleted from the model.

The has been a minor bug fix in the MIP presolve

QP solver will now hot start given a basis and solution