[Coin-lpsolver] Clp Problems

[Kyle Ellrott]

> What it means is that the code expects a variable at its lower bound 
> to have a positive reduced cost or at least >= -tolerance.  An assert 
> failure would tend to indicate that the problem is badly scaled.
>
> However the solution is to refresh your copy of Clp.  That assert is 
> now at line 2084 AND commented out.  I did that some weeks ago as for 
> some reason CBC was being handed nastier problems - maybe because of 
> changes to cut generators.

Thank you.  That got rid of the assertion problem.  Now Cbc doesn't 
return an optimal answer.  In the output I get

Clp0001I Primal infeasible - objective value 32949.4
Cbc3007W No integer variables - nothing to do
Clp0006I 0  Obj 32949.4 Primal inf 267 (267)
Clp0006I 0  Obj 32949.4 Primal inf 267 (267)
Clp0001I Primal infeasible - objective value 32949.4
Clp0006I 0  Obj 32949.4 Primal inf 267 (267) Dual inf 4.70069e-05 (2)
Clp0001I Primal infeasible - objective value 32949.4
Cbc0006I The LP relaxation is infeasible or too expensive

Is this mostly likely the results of my constraint matrix being 
improperly set up, or because I've failed to setup some options 
correctly.
In this particular case, the objective function has 160378 integer 
varibles, and the constraint matrix has 321468 elements.  Would this be 
considered 'too expensive' with the default parameters, or should I be 
checking to make sure it's not because of an incorrect constraint 
matrix?


Thank you for you help,

Kyle





> Kyle Ellrott <kellrott at csbl.bmb.uga.edu>
> Sent by: coin-lpsolver-bounces at list.coin-or.org
>
> 01/10/2005 01:50 PM
>
> To
> coin-lpsolver at list.coin-or.org
>
> cc
>
> Subject
> [Coin-lpsolver] Clp Problems
>
>
>
>
>
>
>
> I'm currently working on some software that uses the Cbc module to
>  solve an integer programming problem.  While I'm not confident that my
>  constraint matrix has been set up correctly, as far as I know, it
>  should be fine.
>  I was wondering if anyone could help figure out what set of events
>  would trigger the following assertion:
>
>  ClpSimplexDual.cpp:2031: failed assertion
>  `oldValue>=-dualTolerance_*1.0001'
>
>  What kind of problems is their assertion typically in response to?
>
>  Thanks,
>
>  Kyle
>
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