[Coin-bcpdiscuss] Default select_branching_candidates bug?

[Laszlo Ladanyi]

That exception is thrown when BCP 
1) can't add a cut/variable and
2) can't fathom the node based on bounds and
3) can't find a branching variable. 
If all three conditions are met then something is wrong. It may be that there
are slight numerical problems, and the LP value is just slightly different
from the value of the solution found. Playing with tolerances a bit would
probably help. I don't remember off the top of my head what parameters to set,
I would have to look up in the source. I'd suggest first to try to turn on all
verbosity parameters to see if rounding errors are erally the problem.

Hope this helps,
--Laci

On Mon, 20 Mar 2006, Lasse Nisted wrote:

> Hello
> 
> Is there a reason why the default select_branching_candidates
> function in BCP_lp_user throws an exception if no
> branching candidates are found?
> Shouldn't it just return BCP_DoNotBranch_Fathomed ?
> 
> Or am I missing something?
> 
> I have a IP problem which is solved to integer optimality in the root node,
> and then the select_branching_candidates throws an exception because
> no columns are generated and no fractional values exist.
> 
> - Lasse
> 
> _______________________________________________
> Coin-bcpdiscuss mailing list
> Coin-bcpdiscuss at list.coin-or.org
> http://list.coin-or.org/mailman/listinfo/coin-bcpdiscuss
>