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Re: Precision of doubles and stdio
- From: skaller <skaller at users dot sourceforge dot net>
- To: Roberto Bagnara <bagnara at cs dot unipr dot it>
- Cc: tprince at computer dot org, cygwin at cygwin dot com, "The Parma Polyhedra Library developers' list" <ppl-devel at cs dot unipr dot it>
- Date: Mon, 06 Mar 2006 00:10:16 +1100
- Subject: Re: Precision of doubles and stdio
- References: <4408B886.5010209@cs.unipr.it> <4408C140.9030100@myrealbox.com> <440ACF12.7000403@cs.unipr.it>
On Sun, 2006-03-05 at 12:44 +0100, Roberto Bagnara wrote:
> Tim Prince wrote:
> My
> > past reading of various relevant documents convinced me that digits
> > beyond the 17th in formatting of doubles are not required by any
> > standard to be consistent between implementations. They have no useful
> > function, as 17 digits are sufficient to determine uniquely the
> > corresponding binary value in IEEE 754 format.
>
> Thank you Tim. We were unaware of this giant bug in the C standard.
> All the best,
There is no bug in the C Standard. The C standard makes it
clear the accuracy of floating point operations is
implementation defined ,and the implementor may even say the
accuracy is undefined.
This is not a bug, it is the proper thing for a language
standard.
--
John Skaller <skaller at users dot sourceforge dot net>
Async PL, Realtime software consultants
Checkout Felix: http://felix.sourceforge.net
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