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## [Help-glpk] Failure with a basic LP problem

**From**: |
Jean-Sebastien Roy |

**Subject**: |
[Help-glpk] Failure with a basic LP problem |

**Date**: |
Tue, 12 Aug 2003 10:33:18 +0200 (CEST) |

I've just come across the following problem :
Minimize
test: a
Subject To
c1: - a + b >= -6909301372.79
c2: - a + c >= -6919351684.21
c3: - a + d >= -6930335991.34
End
for which a=b=c=d=0 seems to be an obvious solution (cplex agrees).
Yet glpk (4.0) gives the following answer :
lpt_read_prob: reading LP data from `bug-glpk2.lp'...
lpt_read_prob: 4 variables, 3 constraints
lpt_read_prob: 7 lines were read
lpx_simplex: original LP has 3 rows, 4 columns, 6 non-zeros
lpx_simplex: presolved LP has 3 rows, 4 columns, 6 non-zeros
gm_scal: max / min = 1.000e+00
gm_scal: max / min = 1.000e+00
lpx_adv_basis: size of triangular part = 3
0: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
1: objval = 0.000000000e+00 infeas = 9.999999856e-01 (0)
2: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
3: objval = 0.000000000e+00 infeas = 9.999999855e-01 (0)
PROBLEM HAS NO FEASIBLE SOLUTION
lpx_simplex: cannot recover undefined or non-optimal solution
Time used: 0.0 secs
Memory used: 0.1M (72700 bytes)
The previous failures I had with glpk came from scaling problems. Is it
still the case is this problem ?
Thank you very much in advance,
Regards,
js

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**[Help-glpk] Failure with a basic LP problem**,
*Jean-Sebastien Roy* **<=**