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

[Rainer M Krug]

(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
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-- 
Rainer M. Krug

email: RMKrug<at>gmail<dot>com