[Coin-discuss] Global cuts

[Laszlo Ladanyi]

I can very well imagine someone wanting to generate cuts based on only
a subset of the currently existing constraints (especially if cut
generation takes place elsewhere than solving LPs does). In that case
creating a SolverInterface object just to pass in the data (since no
LP will be solved by that solverinterface) can be really harmful to
the performance. Not just the copying (that would not be a big deal,
after all, most likely the matrix is going to be scanned several time,
so one extra scan does not matter), but the extra allocation of memory
needed to store the extra copy of the matrix may force paging, which
is bad.

--Laci

On Wed, 29 Jan 2003, Robin Lougee-Heimer wrote:

> Laci:
> 
> >Basically I'd like to
> >make it possible to pass in the problem description and solution in some
> other
> >way than passing in a solverinterface.
> 
>  What's the benefit/motivation for  passing in the packed matrix and primal
> solution as oppose to a reference to the solver interface?
> 
> Robin
> 
> 
> ----------------------------------------------------------------------------------
> 
> Robin Lougee-Heimer
> IBM TJ Watson Research Center
> ph: 914-945-3032   fax: 914-945-3434
> robinlh at us.ibm.com
> http://www.coin-or.org
> 
> 
> 
> ladanyi at watson.ibm.com@www-124.southbury.usf.ibm.com on 01/29/2003 02:52:12
> PM
> 
> Please respond to coin-discuss at www-124.southbury.usf.ibm.com
> 
> Sent by:    coin-discuss-admin at www-124.southbury.usf.ibm.com
> 
> 
> To:    coin-discuss at www-124.southbury.usf.ibm.com
> cc:
> Subject:    Re: [Coin-discuss] Global cuts
> 
> 
> 
> Sounds like a good idea...
> 
> While we are talking about ideas: I propose to add a couple of more
> generateCuts() methods to the cut generator base class. Basically I'd like
> to
> make it possible to pass in the problem description and solution in some
> other
> way than passing in a solverinterface. Like passing in a packed matrix and
> a
> pointer to the primal solution, or passing in a set of pointers (i.e., a
> C-style interface).
> 
> Any objections?
> 
> --Laci
> 
> On Tue, 28 Jan 2003, John J Forrest wrote:
> 
> >
> > I wish to add a bool flag to OsiCut to say if it has global validity.
> >
> > Any objections?
> >
> > John Forrest
> >
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