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Re: What is acceptable for -ffast-math? (Was: associative law incombine)
- To: Linus Torvalds <torvalds at transmeta dot com>
- Subject: Re: What is acceptable for -ffast-math? (Was: associative law incombine)
- From: Gabriel Dos_Reis <gdosreis at sophia dot inria dot fr>
- Date: Wed, 1 Aug 2001 19:25:52 +0200 (MEST)
- Cc: Tim Hollebeek <tim at hollebeek dot com>, Theodore Papadopoulo <Theodore dot Papadopoulo at sophia dot inria dot fr>, Gabriel Dos Reis <gdr at codesourcery dot com>, <dewar at gnat dot com>, <amylaar at redhat dot com>, <aoliva at redhat dot com>, <gcc at gcc dot gnu dot org>, <moshier at moshier dot ne dot mediaone dot net>, <tprince at computer dot org>
- References: <20010801122417.A2509@cj44686-b.reston1.va.home.com><Pine.LNX.4.33.0108010929020.20829-100000@penguin.transmeta.com>
| Now, show me a case where a/b/c -> a/(b*c) is significantly less accurate?
On a 64-bit double processor just take
b = c = 2 * sqrt(DBL_MAX);
a = 0.5 * DBL_MAX
a/(b*c) is 0.0 whereas a/b/c yields 0.125.
-- Gaby