From: fjh@cs.mu.OZ.AU (Fergus Henderson) Subject: Re: Floating Point Usage 3 May 1998 05:15:03 -0700 Message-ID: <19980503183508.41218.cygnus.gnu-win32@murlibobo.cs.mu.OZ.AU> References: <01BD74F3.48BA8460@ts51ip86.cadvision.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Dan Paslawski Cc: "'gnu-win32@cygnus.com'" On 01-May-1998, Dan Paslawski wrote: > I am porting an application from Linux to Windows NT which makes intensive > usage of floating point operations. I am finding slight differences in calculations > between Linux (GNU Version ??) and Windows NT (using Cygwin32 B19.0), on the > same machine. To > be specific, floating point operations such as multiplication and division are > occasionally producing differences (Linux vs WinNt) on the order of one or two bits. > I would have thought the two OS's should produce identical results. On x86, the floating point registers have more precision than `double'; thus the results of a computation may depend on when the compiler flushes intermediate results from registers to memory. Compiling with a different version of the compiler or with different optimization flags may lead to different results, even on the same OS. -- Fergus Henderson | "I have always known that the pursuit WWW: | of excellence is a lethal habit" PGP: finger fjh@128.250.37.3 | -- the last words of T. S. Garp. - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request@cygnus.com" with one line of text: "help".