[Coin-discuss] CBC applied to maximization problems

[Hart, William E]

Mike:

But how does the wrapper know when to flip, if it's simply being handed an LP file?  Do I need to parse the LP file before CBC does?

I can't think of a way of dealing with this that isn't kludgey.  

--Bill 

> -----Original Message-----
> From: Michael Hennebry [mailto:hennebry at web.cs.ndsu.nodak.edu] 
> Sent: Tuesday, December 02, 2008 8:27 PM
> To: Hart, William E
> Cc: fmargot at andrew.cmu.edu; coin-discuss at list.coin-or.org
> Subject: Re: [Coin-discuss] CBC applied to maximization problems
> 
> On Tue, 2 Dec 2008, Hart, William E wrote:
> 
> > Here's my scenario.  I have a wrapper script that passes a 
> LP or MPS file to CBC, and then parses the output.  The 
> results of this optimization process are then returned to the 
> user.  The confusing thing is that a user sees minimization 
> results when passed a maximization problem.  Logically, it's 
> identical, but this will be surprising and confusing to 
> non-technical users.
> 
> I think that the answer is to have the wrapper do the flipping.
> The wrapper can print the warning.
> The wrapper could also negate any output that needed negating.
> 
> > If CBC/CoinLpIO simply printed a warning that this problem 
> was being reformulated, that would be enough for me to 
> correctly parse the output.  (Working with the library 
> directly, this wouldn't be an issue because I could check the 
> max/min sense of the original problem...).
> 
> -- 
> Michael   hennebry at web.cs.ndsu.NoDak.edu
> "Pessimist: The glass is half empty.
> Optimist:   The glass is half full.
> Engineer:   The glass is twice as big as it needs to be."
> 
>