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NNTP-Posting-Date: Fri, 09 May 2014 18:00:45 -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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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
>
> Math::BigFloat looks promising (if I would mind to compete with windopws
> calculator), however resourceful.  But it's a way too much hassle for
> now -- it doesn't have btan() and bacos() methods, so those must be
> constructed in place.

gforth:

: PIE 3.1415926535897932385E0 ;

: DEG2RAD PI F* 180E0 F/ ;

: RAD2DEG 180E0 F* PI F/ ;

: TEST 45E0 DEG2RAD FSIN FCOS FTAN FATAN FACOS FASIN RAD2DEG 45E0 F- F. ;

TEST

-0.000000000000007105427357601