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

>

> ______________________________________________

>

[hidden email] mailing list

>

https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide

http://www.R-project.org/posting-guide.html> 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

Policies:

1. I will NOT analyse your data for you.

2. Your deadline is your problem.

The combination of some data and an aching desire for

an answer does not ensure that a reasonable answer can

be extracted from a given body of data. - John Tukey.

______________________________________________

[hidden email] mailing list

https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide

http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.