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Re: Round-off error?

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  • Subject: [mg131942] Re: Round-off error?
  • From: Richard Fateman <fateman at>
  • Date: Mon, 4 Nov 2013 23:17:19 -0500 (EST)
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  • References: <l525kr$9ft$>

On 11/1/2013 11:21 PM, Bill Rowe wrote:

> shows the two machine precision numbers differ by 1 bit and
> consequently are considered equal by Equal as documented.
> This type of issue is inherent in floating point arithmetic done
> on any modern computer.
This is not at all true.  Mathematica chooses to implement a fuzzy
version of equality that does not correspond to any hardware
floating-point operation on any modern computer that I am aware of.

Mathematica's definition of Equal is a misfeature that leads to
many contradictions to ordinary arithmetic results.  This has
been pointed out numerous times and presumably will continue to
provoke questions indefinitely.



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