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Date:	Thu, 30 Oct 2003 08:25:52 -0500
Message-Id:	<200310301325.h9UDPqVF020025@envy.delorie.com>
From:	DJ Delorie <dj AT delorie DOT com>
To:	djgpp AT delorie DOT com
In-reply-to:	<oprxuxfe0j0bb83x@news.mad.ttd.net> (message from
	=?iso-8859-15?Q?Rafael_Garc=EDa?= on Thu, 30 Oct 2003 14:07:52 +0100)
Subject:	Re: double with only 13 digit precision?
References:	<oprxuxfe0j0bb83x AT news DOT mad DOT ttd DOT net>
Errors-To:	nobody AT delorie DOT com
X-Mailing-List:	djgpp AT delorie DOT com
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In this case, the problem is that the two numbers you are subtracting
only have a certain precision *after the decimal*.  The result has
the same number of digits after the decimal as the numbers you start with.
Garbage in, garbage out - try printing them like this:

   printf("%25.18f\n%25.18f\n%25.18f\n",a,b,c);

You'll see:

  4777.909999999999854481
  4782.979999999999563443
    -5.069999999999708962

Note that the 9's all end in the same column.

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