Andrew, There is a bug in the dual simplex transition from phase I to phase II when perturbation was applied - it may be that the perturbed problem is dual infeasible while the unperturbed one is feasible, a case that is not checked in the code. This happens with stat96v1 (downloaded from http://www.sztaki.hu/~meszaros/public_ftp/lptestset/misc/ ).
The attached patch is an approach to fix this, but disables perturbation for phase II in this case, which may not be desirable. Best Regards, Chris Matrakidis
dual.patch
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