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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

and NTL



Paul A Bristow
Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB
Phone and SMS text +44 1539 561830, Mobile and SMS text +44 7714 330204
mailto: pbristow_at_[hidden]

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