Hello GLPK users,
I used glpk (4.15) on my linear programming problem and dumped the result
into a text file. At the beginning of the file, it has the following
message:
<quote>
Rows: 274
Columns: 7576 (7350 integer, 7350 binary)
Non-zeros: 1069
Status: INTEGER OPTIMAL
Objective: obj = 255.0545959 (MINimum)
</quote>
This gave me an impression that the solver found the optimal solution.
When I check the solution file towards the end, I see this message:
<quote>
Integer feasibility conditions:
INT.PE: max.abs.err. = 5.68e-14 on row 150
max.rel.err. = 1.42e-14 on row 2
High quality
INT.PB: max.abs.err. = 4.66e+01 on row 152
max.rel.err. = 9.79e-01 on row 152
SOLUTION IS INFEASIBLE
</quote>
Perhaps I am too novice a user to understand these messages. I don't
understand how an integer optimal solution can be found when
the solution is infeasible. Then again, there are two words
INT.PE and INT.PB which I don't understand (and I googled for the meaning
without much success). I would greatly appreciate any help to make me
understand what is going on.
I used glpsol to solve these. I used --intopt with and without
--nopresol, both giving the same result.
Thanks,
Shreekanth
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