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## Re: [Bug-glpk] [Fwd: BUG report]

**From**: |
Andrew Makhorin |

**Subject**: |
Re: [Bug-glpk] [Fwd: BUG report] |

**Date**: |
Mon, 27 May 2013 22:22:51 +0400 |

>* I think that I found a BUG.*
>* *
>* LP problem*
>* *
>* *
>* Maximize*
>* obj: + 3 Lanac_1 + 5 Lanac_2 + 4 Lanac_3 + 4 Lanac_4 + 3 Lanac_5*
>* *
>* Subject To*
>* C6: + Lanac_5 + Lanac_3 + Lanac_1 <= 1000*
>* C7: + Lanac_3 + Lanac_2 + Lanac_1 <= 560.5*
>* C13: + Lanac_3 + Lanac_2 <= 2500*
>* C12: + Lanac_4 + Lanac_2 <= 855.2*
>* C15: + Lanac_4 + Lanac_2 <= 800*
>* C16: + Lanac_4 + Lanac_2 <= 1000*
>* C14: + Lanac_5 + Lanac_3 <= 700*
>* C11: + Lanac_5 + Lanac_4 <= 254.8*
>* *
>* Bounds*
>* 200 <= Lanac_1 <= 560.5*
>* 200 <= Lanac_2 <= 560.5*
>* 200 <= Lanac_3 <= 560.5*
>* 200 <= Lanac_4 <= 254.8*
>* 200 <= Lanac_5 <= 254.8*
>* *
>* End*
>* *
>* For all my variables I'm getting 200 as a result which is not*
>* correct if we look at constraint C7 or C11:*
>* *
>* C7: + Lanac_3 + Lanac_2 + Lanac_1 <= 560.5*
>* *
>* 600 is not less than 560.5*
Your instance is primal infeasible, i.e. it has no primal feasible
solution; you must see a diagnostic message about that. In this case the
glpk simplex solver returns a basic solution that minimizes the sum of
infeasibilities, and since that solution is primal infeasible, it
violates some constraints.