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<TITLE>Re: [Cgl] Re: Numerical precision in cut generators</TITLE>
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<FONT FACE="Verdana, Helvetica, Arial"><SPAN STYLE='font-size:12.0px'>Good idea to set a default for silence :)<BR>
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I agree that standardization is a good idea, though I don’t have a strong opinion about what the value should be. This value for EPS seems fine. I will ask some of my more numerically savvy collaborators for their opinions.<BR>
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I just reread Francois’ original message (sorry, I didn’t join the mailing list till September). I think it makes sense to have a set of computational precision/tolerance values defined and set to defaults in the base class. Individual cut generators can derive other tolerances from these (if too generator-specific to belong in the base class) and combinatorial ones can ignore them.<BR>
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I’d like to suggest that while we are considering standardized numerical precision, that we also make these values parameters within the cut generators. That is, for the CGs that don’t already do this, replace all hard-coded tolerance/precision values with parameters (derived from a set in the base class if appropriate) and make those parameters adjustable both at the base class level and at the CG level if reasonable. CglRedSplit does this through its setEPS method, for example.<BR>
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Thanks!<BR>
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- Cindy<BR>
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On 9/20/06 7:45 AM, "Robin Lougee-Heimer" <robinlh@us.ibm.com> wrote:<BR>
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In July, Francois proposed using standard variables for handling numerican precision, e.g., <BR>
</SPAN></FONT><SPAN STYLE='font-size:12.0px'><FONT FACE="Monaco, Courier New"> EPS: Precision of double computations. Default value: 1e-7.<BR>
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I agree - we should have a standard. It makes a lot of sense. <BR>
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The list of standards he proposed was based on CglRedSplit, and CglGomory. It seemed a bit of overkill to me, but if they were necessary/useful for Gomory and RedSplit then it seems a reasonable list to begin. <BR>
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----> Does anyone else have any thoughts/comments? <BR>
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Silence will be taken as thunderous approval, and the next step would be asking each CG-maintainer to update their CG. <BR>
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Robin <BR>
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----------------------------------------------------------------------------------<BR>
Robin Lougee-Heimer<BR>
IBM TJ Watson Research Center<BR>
1101 Kitchawan Road, Yorktown Heights, NY 10598<BR>
ph: 914-945-3032 fax: 914-945-3434 <BR>
robinlh@us.ibm.com<BR>
<a href="http://www.coin-or.org">http://www.coin-or.org</a><BR>
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