[Coin-discuss] Setting Upper Bound in BCP

[Francois Margot]

Dan:

BCP works with a granularity (minimum distance between two different values
of feasible solutions) of 1e-8 by default.

This means that if the upper bound is set to -2.0,
BCP is looking for a solution with value smaller than -2.00000001, and
it finds nothing, which is correct. If you want it to report a solution 
with value -2.0, set the upper bound to -1.9, for example.

By the way, it is probably simpler to use the method BB_tm::create_root()
for setting the upper bound instead of BB_init.cpp.

Francois


On Tue, 6 Jun 2006, Dan Chen wrote:

> Hello Everyone,
>
>  I find that when I set the upper bound with the optimal objective value in BB_init.cpp in BAC, the example of using BCP, the program will report infeasibility.
>
>    TM: search tree size: 3 max depth: 1
>  LP statistics:
>  time in cut generation : 0.000 sec
>  time in var generation : 0.000 sec
>  time in heuristics : 0.000 sec
>  time in solving LPs : 0.000 sec
>  time in strong branching: 0.004 sec
>  TM: No feasible solution is found
>
>
>  I also have this problem in my own project. If the heuristic find the optimal solution, the program will report infeasibility.
>
>  P.S. The BB_init.cpp changed by me is attached.
>
>  Best Regards!
>
>  Dan Chen
>
>
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