[Clp] Incorrect solution for LP problem

[John Forrest]

Kish,

Seems to be a change to CoinLpIO - objective is being ignored - 
something to do with no objective name possibly.  Coding has changed for 
CoinlpIO but I am not an expert.  Will look at it tomorrow morning, 
unless whoever made changes to CoinLpIO fixes problem before then.

John

On 22/10/14 18:28, Kish Shen wrote:
> Hi,
>
> I updated CBC yesterday (for dealing with handling of messages via 
> message handlers -- thanks John!), but this CBC is failing one of our 
> existing tests. It looks like the problem is in CLP, as CLP seems to 
> be returning an incorrect objective value for the following LP problem:
>
> \Problem name: eclipse3
>
> Minimize
>   C1
>
> Subject To
> R1: C1 + C2 >= 7
> R2: - C2 + C1 = 0
>
> Bounds
> C1 free
> C2 free
>
> End
>
> The objective should be 3.5, but 0.0 is returned.
>
> I have been able to reproduce this problem using the clp executable --
> by import(ing) the LP file and then solve.
>
> This is from CBC 2.8 that I downloaded yesterday. The problem was not 
> in the earlier CBC 2.8 that I was using, which was probably downloaded 
> about a year ago.
>
> Is this a problem in CLP, or am I doing something wrong?
>
> Thanks in advance for any help/information!
>
> Cheers,
>
> Kish
> _______________________________________________
> Clp mailing list
> Clp at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/clp
>
>