[R] sin(pi)?

[Peter Dalgaard]

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
>   
Well, sin(pi) is theoretically zero, so you are just seeing zero at two 
different levels of precision.

The built-in pi has more digits than it displays:

 > pi
[1] 3.141593
 > pi - 3.141593
[1] -3.464102e-07
 > print(pi, digits=20)
[1] 3.141592653589793

> ____________________________
> Nguyen Dinh Nguyen
> Garvan Institute of Medical Research
> Sydney, Australia
>
>   
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