[Coin-bcpdiscuss] Re: Coin-bcpdiscuss Digest, Vol 18, Issue 1

[Daniel Fleischman]

> My other problem is still there. I retrieve the dual vector as follows:
> In compute_lower_bound, I receive the current LP solution in the
> argument lpres (of type const BCP_lp_result&). I retrieve the dual
> vector through:
> 	const double* pi = lpres.pi();
> In this way, in the second iteration, I get the same dual vector
> (pi[.]=1.0 for all cuts) as in iteration 1, although the LP primal
> solution (Z_LP) has a lower value. And I believe that for a set covering
> problem with all column costs = 1, we should have
> 	sum(pi[.]) = Z_LP = sum(x[.])
> But in my case, in iteration 2, I have
> 	sum(pi[.]) <> Z_LP = sum(x[.])
> Any thoughts on this one?



I am sorry I've reopened this old thread, but I am having exactly the same
problem, and can't get through it. Can anyone help me, with this one? I am
completely lost, it seems like BCP simply doesn't give me the right dual
vector.

Thank you in advance,
Daniel Fleischman.
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