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Re: [Bug-glpk] glpsol ignores tmlim
From: |
Andrew Makhorin |
Subject: |
Re: [Bug-glpk] glpsol ignores tmlim |
Date: |
Fri, 4 Sep 2009 15:26:12 +0400 |
Hi Xypron,
> when starting glpsol for the model file below with
> glpsol -m test.mod --tmlim 100
> the solver does not terminate within the required time.
> A lot of lines like the following are output:
> | 19400: obj = 6.400000000e+001 infeas = 7.062e-014 (2)
> | 19600: obj = 6.400000000e+001 infeas = 1.024e-014 (2)
> | 19800: obj = 6.400000000e+001 infeas = 5.663e-014 (2)
Thank you for your bug report.
The solver does not stop, because the time limit is checked at the
beginning of the branch-and-bound loop, however, the dual simplex is
cycling and does not return.
BTW, your instance is pathological (currently I am trying to analyze
it). Though it is well scaled, in optimal solution to lp relaxation
some constraints have huge reduced costs that explains why the dual
simplex cannot terminate:
131 move[2,1,1] B 0 0
132 move[2,1,2] NU 0 0 < eps
133 move[2,1,3] NU 0 0 1.28218e+20
134 move[2,1,4] NU 0 0 < eps
135 move[2,1,5] NU 0 0 1.42691e+20
136 move[2,1,6] NU 0 0 < eps
137 move[2,1,7] NU 0 0 9.93974e+19
138 move[2,1,8] NU 0 0 < eps
139 move[2,2,1] B 0 0
140 move[2,2,2] NU 0 0 1.42098e+20
141 move[2,2,3] B -0.317426 0
142 move[2,2,4] NU 0 0 2.09366e+20
143 move[2,2,5] NU 0 0 < eps
144 move[2,2,6] NU 0 0 1.90904e+20
145 move[2,2,7] NU 0 0 < eps
146 move[2,2,8] NU 0 0 9.94232e+19
147 move[2,3,1] NU 0 0 1.28218e+20
148 move[2,3,2] B -0.682574 0
149 move[2,3,3] NU 0 0 2.55832e+20
150 move[2,3,4] NU 0 0 < eps
Andrew Makhorin