Re: [boost] [math] floating point classification - testinghelpwanted

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2005-12-02 07:57:36

| -----Original Message-----
| From: boost-bounces_at_[hidden] 
| [mailto:boost-bounces_at_[hidden]] On Behalf Of John Maddock
| Sent: 02 December 2005 12:22
| To: boost_at_[hidden]
| Subject: Re: [boost] [math] floating point classification - 
| testinghelpwanted
| 

| but there's at least one 
| problem case: 
| long double's on Darwin.  I can't find any information on 
| these after a 
| quick google search, but I believe they're effectively a sum 
| of two doubles. 
| If so this is exceptionally bad form because it violates the most 
| fundamental principal of IEEE arithmatic that a number is n*2^k. 
| (Background: epsilon is very small for this type, it's 
| possible to add a 
| number "delta" to 1.0L and still get a distict value when 
| "delta" is much 
| smaller than the number of bit's in a long double would 
| otherwise indicate. 
| This makes a *lot* of IEEE based reasoning invalid.  If 
| anyone has more 
| information on this type I'd appreciate a reference).

Is the the same as doubledouble by Keith Briggs

http://keithbriggs.info/xrc.html

and NTL

http://www.shoup.net/ntl/

?

Paul

-- 
Paul A Bristow
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