Is it possible to pass a HighsBasis built manually?

[fontanf]

Hi,

Are the basis returned by getBasis and passed to setBasis for the original model? That is, can I create my own HighsBasis and pass it to Highs with setBasis? If yes, what happen if the basis is wrong, will Highs try to fix it?

[jajhall]

Yes, any basis communicated to/from HiGHS corresponds to the original model.

You can create your own basis and pass it to HiGHS with setBasis. It doesn't even need to have the right number of basic and nonbasic variables - so it can be rectangular (either way) - and the basic columns can be linearly dependent - or almost linearly dependent, which is just as bad. HiGHS will factorize the matrix corresponding to what you say is basic and, when it stops due to the matrix having a lower rank than the number of constraints (or because it would have to pivot on a number that's too small), it will complete the basis with slack variables.