bug-glpk
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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.

```