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From: jody <jod...@gm...> - 2010-02-08 16:18:37
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Hi Unless some gnuplot versions work with 32bit floats, I'm surprised that it wouldn't work, because 100! = 9.33262154439442e+157 which is well inside the range of a (64bit) double... Jody >> > exponentiate at the end (if needed). On Mon, Feb 8, 2010 at 5:04 PM, Philipp K. Janert <ja...@ie...> wrote: > On Monday 08 February 2010 07:53:24 am Tim Wojtulewicz wrote: >> On Mon, Feb 08, 2010 at 07:15:21AM -0800, Philipp K. Janert wrote: >> > On Sunday 07 February 2010 11:07:07 am Tim Wojtulewicz wrote: >> > > I'm working with a fairly complicated function, one part of which is >> > > the division of two factorials. I'm having an issue with though, >> > > because gnuplot keeps returning NaN for what should be a simple >> > > division. It will return NaN for something as simple as 100!/99!, >> > > which should just be 100. Is there a reason for this, or an easy way to >> > > fix it? Thanks. >> > >> > The intermediate results overflow, despite the fact that >> > the final result is of meaningful size. >> > >> > Either work out the cancellations analytically, or work with >> > logarithms of all quantities (Stirlings approximation!), and >> > exponentiate at the end (if needed). >> >> So is this a version issue then? The reply from Thomas seems like his >> is working correctly. I'm working with version 4.2.5 on OS X 10.6. >> It's odd that his would work, and yet mine won't. > > If anything, this is a platform issue. Quite frankly, > I was surprised that it worked for anybody. (It doesn't > for me.) > > But this is besides the point: if you need factorials > of large numbers (>10), then you need to find ways > to tame overflow issues. Unless you are working in > infinite precision integer arithmetic, which is not > something that gnuplot does. > >> >> Tim >> >> --------------------------------------------------------------------------- >>--- The Planet: dedicated and managed hosting, cloud storage, colocation >> Stay online with enterprise data centers and the best network in the >> business Choose flexible plans and management services without long-term >> contracts Personal 24x7 support from experience hosting pros just a phone >> call away. http://p.sf.net/sfu/theplanet-com >> _______________________________________________ >> gnuplot-info mailing list >> gnu...@li... >> https://lists.sourceforge.net/lists/listinfo/gnuplot-info > > > > ------------------------------------------------------------------------------ > The Planet: dedicated and managed hosting, cloud storage, colocation > Stay online with enterprise data centers and the best network in the business > Choose flexible plans and management services without long-term contracts > Personal 24x7 support from experience hosting pros just a phone call away. > http://p.sf.net/sfu/theplanet-com > _______________________________________________ > gnuplot-info mailing list > gnu...@li... > https://lists.sourceforge.net/lists/listinfo/gnuplot-info > |