[Coin-discuss] BCP_LpValueIsTrueLowerBound

[Laszlo Ladanyi]

Thanks for finding this feature (errr, bug :-)! Now the default
compute_lower_bound() returns lpres.objval() if the LpValueIsTrueLowerBound
parameter is set.

--Laci

On Mon, 22 Sep 2003, Matthew Galati wrote:

> in the case where you are doing pricing, but you know the LP is a true 
> lower bound, the user should not have to derive compute_lower_bound
> 
> i noticed that BCP_LpValueIsTrueLowerBound is never actually used
> 
> [mgalati at localhost Bcp]$ grep "BCP_LpValueIsTrueLowerBound" */*.*
> TM/BCP_tm_param.cpp: 
> keys.push_back(make_pair(BCP_string("BCP_LpValueIsTrueLowerBound"),
> 
> compute_lower_bound defaults to return the "old_lower_bound" when column 
> generation is done... this would cause an error in the case where the 
> very first iteration gives the optimal IP value
> 
> BCP_LpValueIsTrueLowerBound should probably be included in the default 
> compute_lower_bound function
> 
> a work around is for the user to always derive compute_lower_bound... in 
> this case, simply return lpres.objval();
> 
> 
> Matt
> 
> 
> -- 
> Matthew Galati
> ISE Lehigh University
> IBM Service Parts Solutions
> 610.758.4042 (Office)
> 610.882.0779 (Home)
> magh at lehigh.edu, magal11 at us.ibm.com
> http://sagan.ie.lehigh.edu/mgalati/
> 
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