[Clp-tickets] Re: [COIN-OR Linear Programming Solver] #15: Feasible problem returns infeasible; inconsistent results

[COIN-OR Linear Programming Solver]

#15: Feasible problem returns infeasible; inconsistent results
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  Reporter:  ltaylor     |       Owner:  somebody
      Type:  defect      |      Status:  new     
  Priority:  major       |   Milestone:          
 Component:  component1  |     Version:          
Resolution:              |    Keywords:          
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Comment (by jpfasano):

 LAT states:
 {{{
 if I load the same file and use command 'primals', clp.exe reports that
 the problem is feasible. As I know from solving it previously, the correct
 solution has an objective of 4.87.
 }}}
 This is not what happens for me. 'primals' reports the problem as
 infeasible:
 {{{
 D:\COIN\Coin-Clp-All\trunk\Clp\MSVisualStudio\v8\clp\Release>clp
 Coin LP version 1.06.00, build Nov 17 2007
 Clp takes input from arguments ( - switches to stdin)
 Enter ? for list of commands or help
 Clp:import ch108-prob1.mps
 At line 1 NAME          BLANK
 At line 2 ROWS
 At line 98 COLUMNS
 At line 11210 RHS
 At line 11211 BOUNDS
 At line 13581 ENDATA
 Problem BLANK has 94 rows, 2369 columns and 17942 elements
 Model was imported from .\ch108-prob1.mps in 0.03 seconds
 Clp:primals
 Presolve 72 (-22) rows, 2323 (-46) columns and 17764 (-178) elements
 Perturbing problem by 0.001 % of 7682.26 - largest nonzero change
 0.0240588 (% 0.056856) - largest zero change 0
 0  Obj 0 Primal inf 31.313 (16) Dual inf 1.89922e+013 (386)
 76  Obj 1.45628e-005 Primal inf 0.0468318 (13) Dual inf 2.28393e+008 (198)
 137  Obj 3.25773e-005 Primal inf 0.0468206 (13)
 147  Obj 2.41675e-005 Primal inf 0.0443591 (3) Dual inf 242.045 (128)
 156  Obj 2.36299e-005 Primal inf 0.0443591 (3) Dual inf 2.444 (64)
 160  Obj 2.46491e-005 Primal inf 0.0443591 (3) Dual inf 4.64826 (61)
 163  Obj 2.4318e-005 Primal inf 0.0443591 (3) Dual inf 1.32923 (38)
 168  Obj 2.41847e-005 Primal inf 0.0443591 (3) Dual inf 1.34902 (30)
 171  Obj 2.62022e-005 Primal inf 0.0443591 (3) Dual inf 0.387188 (16)
 175  Obj 2.73519e-005 Primal inf 0.0443591 (3) Dual inf 0.0494242 (3)
 177  Obj 2.71674e-005 Primal inf 0.0443591 (3)
 Primal infeasible - objective value 2.71674e-005
 Presolved problem not optimal, resolve after postsolve
 After Postsolve, objective 2.71674e-005, infeasibilities - dual 0.00104051
 (333), primal 3903.52 (6)
 PrimalInfeasible objective 2.716742009e-005 - 354 iterations time 0.072,
 Presolve 0.02
 Clp:
 }}}
 I used the current trunk version of Clp built with the Microsoft V8
 compiler solution file.

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Ticket URL: <https://projects.coin-or.org/Clp/ticket/15#comment:1>
COIN-OR Linear Programming Solver <http://projects.coin-or.org/Clp>
A linear programming solver.