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Subject: Re: Precision of doubles and stdio
From: skaller <skaller@users.sourceforge.net>
To: Roberto Bagnara <bagnara@cs.unipr.it>
Cc: tprince@computer.org, cygwin@cygwin.com,
   "The Parma Polyhedra Library developers' list" <ppl-devel@cs.unipr.it>
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Date: Mon, 06 Mar 2006 00:10:16 +1100
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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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