Matrix files

With Xpress, the user has the choice between two matrix formats: extended MPS and extended LP format, the latter being in general more easily human-readable since constraints are printed in algebraic form. Such matrices may be written out by Xpress Optimizer, but more likely they will have been generated by some other tool.

If the optimization process with Xpress Optimizer is started from within a Mosel or BCL program, then the problem matrix is loaded in memory into the solver without writing it out to a file (which would be expensive in terms of running time). However, both tools may also be used to produce matrix files (see Chapter 9 for matrix generation with Mosel and Chapter 10 for BCL).