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List:       perl6-language
Subject:    Re: Comparing inexact values (was "Re: Temporal changes")
From:       Jon Lang <dataweaver () gmail ! com>
Date:       2009-02-27 1:27:57
Message-ID: ef30550b0902261727w29ee06b0paf6dcdaf7b3bdd5a () mail ! gmail ! com
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Martin D Kealey wrote:
> On Thu, 26 Feb 2009, Jon Lang wrote:
>> asin is not the inverse function of sin, although it's probably as close
>> as you can get.   And even there, some sort of compiler optimization could
>> potentially be done, replacing the composition of asin and sin (both of
>> which have the potential to intensify error) with a normalization of the
>> value into the -pi ..^ pi range (which might also introduce error).
>
> Hmmm ... the normal mathematical range of arc-sine is (-π,+π], rather than
> [-π,+π), especially where complex numbers are concerned: arg(-1) == +π.
> (Well, so much for consistently using lower half-open ranges.)

...you're right.  Sorry; my error.

-- 
Jonathan "Dataweaver" Lang

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