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Re: Comparisson operators

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From Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups comp.lang.javascript
Subject Re: Comparisson operators
Date Tue, 29 Sep 2015 19:39:09 +0200
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Ben Bacarisse wrote:

> jonas.thornvall@gmail.com writes:
>> And what happen if you try to compare elements that is bigger than the
>> scope of javascript integers?
> 
> A normal floating-point comparison is done, just as it always is.  What
> matters is the range of integer values that can be represented exactly.
> That range is -(2**53 - 1) to 2**53 - 1.  The latest ECMAScript defines
> property, Number.MAX_SAFE_INTEGER with the value 9007199254740991, but
> you can always calculate Math.pow(2, 53) - 1.

This description is so imprecise as to be misleading.  Several integers 
smaller and greater than these boundaries can be stored exactly, but the 
integers *between* the boundaries and the stored integers cannot be, because 
the achievable precision is insufficient.  Insofar Number.MIN_SAFE_INTEGER 
and Number.MAX_SAFE_INTEGER only give the minimum/maximum integer down/up to 
which proper arithmetic is possible (hence “SAFE”).

The minimum/maximum integer than can be represented exactly with IEEE 754 
doubles is approximately ±1.8 × 10³⁰⁸; it is exactly given by
-Number.MAX_VALUE and Number.MAX_VALUE, respectively.  (Note that 
Number.MIN_VALUE gives the smallest floating-point value greater than 0 
instead.)

-- 
PointedEars
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Thread

Comparisson operators jonas.thornvall@gmail.com - 2015-09-28 23:24 -0700
  Re: Comparisson operators "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2015-09-29 12:16 +0200
  Re: Comparisson operators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-29 12:24 +0100
    Re: Comparisson operators Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-09-29 19:39 +0200
  Re: Comparisson operators Silvio <silvio@internet.com> - 2015-09-30 13:28 +0200

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