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NNTP-Posting-Date: Fri, 09 May 2014 13:06:32 -0500
From: David Hume <David.Hume@example.com>
Newsgroups: comp.misc
Subject: Re: Calculator Accuracy
References: <lkfa27$661$1@dont-email.me> <mtHav.235783$vM2.115843@fx18.am4> <83k39w1tnl.fsf@example.com> <lkfom3$7ui$1@speranza.aioe.org> <slrnlmphuk.12h.whynot@orphan.zombinet>
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Xref: csiph.com comp.misc:2728

Eric Pozharski <whynot@pozharski.name> writes:

> with <lkfom3$7ui$1@speranza.aioe.org> Hils wrote:
>
> *SKIP*
>> R version 3.1.0:
>>
>> asin(acos(atan(tan(cos(sin(45*pi/180))))))*180/pi-45
>> [1] -7.105427e-15
>>
>> Gnuplot 4.6:
>>
>> print asin(acos(atan(tan(cos(sin(45*pi/180))))))*180/pi-45
>> -7.105427357601e-15
>>
>> I'm guessing a common library at work here...
>
> libc, maybe:
>
> 	% perl -MMath::Trig -wle '
> 	print rad2deg( asin acos atan tan cos sin deg2rad 45 ) - 45'
> 	7.105427357601e-15
>

These aren't the same tests as having the calculator in degrees mode,
because in these tests when the result of sine is passed to cosine it is
treated as radians.