[R] Why does sin(pi) not return 0?

[John Kane]

Definitely a Fortune.

John Kane
Kingston ON Canada


> -----Original Message-----
> From: rainer at krugs.de
> Sent: Thu, 26 Sep 2013 11:30:27 +0200
> To: r-help at stat.math.ethz.ch
> Subject: Re: [R] Why does sin(pi) not return 0?
> 
> (Ted Harding) <Ted.Harding at wlandres.net> writes:
> 
>> On 26-Sep-2013 07:55:38 Rolf Turner wrote:
>>> On 09/26/13 19:31, Babak Bastan wrote:
>>>> Hi experts,
>>>> 
>>>> If I test sin(pi) in r, it returns me 1.224606e-16
>>>> 
>>>> Why doesn't return me 0?
>>> 
> 
> I think this should be a Fortune:
> ,----
> | >> If you think that 1.224606e-16 is different from 0, you should
> probably not
> | >> be using computers.
> | >
> | > Is that a Fortune? And, if so, should R be using computers?
> | >
> | >   sin(pi)
> | >   # [1] 1.224606e-16
> | >   sin(pi)==0
> | >   # [1] FALSE
> `----
> 
> Cheers,
> 
> Rainer
> 
>> 
>>> See FAQ 7.31 (which is in a way about the inverse of
>>> your question, but it should provide the necessary insight).
>>> 
>>>      cheers,
>>>      Rolf Turner
>> 
>> Though, mind you, FAQ 3.71 does also offer some consolation to R:
>> 
>>   all.equal(0,sin(pi))
>>   # [1] TRUE
>> 
>> So it depends on what you mean by "different from". Computers
>> have their own fuzzy concept of this ... Babak has too fussy
>> a concept.
>> 
>> Ted.
>> 
>> -------------------------------------------------
>> E-Mail: (Ted Harding) <Ted.Harding at wlandres.net>
>> Date: 26-Sep-2013  Time: 09:13:33
>> This message was sent by XFMail
>> 
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> 
> --
> Rainer M. Krug
> 
> email: RMKrug<at>gmail<dot>com
> 
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