[Clp] MpsTolerance

[Ahmadi, Javad]

John,

This would be a useful addition.

 

On a separate topic, I have had some bad experiences with the pre-solve
routine.  For large problems that  involve a great deal of reduction
pre-solve crashes with an OS memory error.  I tried some cases where we
were trying a " do nothing" solution by forcing all primary decision
variables to zero.  Pre-solve in some cases took much longer time to
solve the problem than normal cases and in some cases it crashed.  Is
there a chance for someone to take a look at the code for potential
issues.

thanks

 

From: clp-bounces at list.coin-or.org [mailto:clp-bounces at list.coin-or.org]
On Behalf Of John J Forrest
Sent: Wednesday, February 11, 2009 4:14 AM
Cc: clp at list.coin-or.org
Subject: Re: [Clp] MpsTolerance

 

In CoinMpsIO.cpp tinyElement is hard coded as 1.0e-14.

In Clp, when primal or dual is entered all values < smallElement_ are
treated as zero. This has default value of 1.0e-20 and can be changed by
setSmallElement.

If there was a general feeling that it would be useful to have a
function like ekk_setRtolmps then it would be easy to add smallElement_
to CoinMpsIO.?pp and let Clp use max of ClpModel::smallElement_ and
CoinMpsIO::smallElement_ when reading an Mps file.

John Forrest

 Emrah Tanriverdi ---02/10/2009 03:02:15 PM---Hi,

 
From:

 
Emrah Tanriverdi <emrahtanriverdi at yahoo.com>


To:


clp at list.coin-or.org


Date:


02/10/2009 03:02 PM


Subject:


[Clp] MpsTolerance

________________________________




Hi,

Is there setting mps tolerance function in CLP, I know there is one in
OSL as following
// Set MPS file tolerance so that very small numbers
// are considered zero.
ekk_setRtolmps(myModel, mpsTolerance);
Thanks,
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