[R] sin(pi)?

[Simon Blomberg]

Umm. pi has been rounded to 6 decimal places in the second example. So
it isn't surprising that the results differ. sin(pi) is not zero, as it
also has been rounded, and you can't represent irrational numbers
exactly in a numerical form anyway. R agrees with Octave:

octave:1> sin(pi)
ans =  1.2246e-16
octave:2> sin(3.141593)
ans =  -3.4641e-07
octave:3> 

To paraphrase someone else on this list: I think it is strange that you
think it is strange.

Simon.

As someone On Mon, 2007-09-03 at 16:43 +1000, Nguyen Dinh Nguyen wrote:
> Dear all,
> I found something strange when calculating sin of pi value
> sin(pi)
> [1] 1.224606e-16
> 
>  pi
> [1] 3.141593
> 
>  sin(3.141593)
> [1] -3.464102e-07
> 
> Any help and comment should be appreciated. 
> Regards
> Nguyen
> 
> ____________________________
> Nguyen Dinh Nguyen
> Garvan Institute of Medical Research
> Sydney, Australia
> 
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> and provide commented, minimal, self-contained, reproducible code.
-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
Faculty of Biological and Chemical Sciences 
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506 
email: S.Blomberg1_at_uq.edu.au

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