R devel - Feb 2009 - Logical Error? (PR#13516)

Full_Name: Suzi Alves Camey
Version: 2.7.2
OS: 
Submission from: (NULL) (143.54.37.254)


Using the commands bellow I expected that the answer is TRUE, but it is FALSE!

P_exposicao=.9
(1-P_exposicao)==.1

This is not a bug.  Please do read the FAQ before posting and creating
work for others.
http://cran.r-project.org/doc/FAQ/R-FAQ.html#R-Bugs
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f

Joshua Ulrich
--
http://quantemplation.blogspot.com



On Tue, Feb 10, 2009 at 8:55 AM,  <camey at mat.ufrgs.br>
wrote:
> Full_Name: Suzi Alves Camey
> Version: 2.7.2
> OS:
> Submission from: (NULL) (143.54.37.254)
>
>
> Using the commands bellow I expected that the answer is TRUE, but it is
FALSE!
>
> P_exposicao=.9
> (1-P_exposicao)==.1
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

Excerpts from camey's message of Tue Feb 10 15:55:04 +0100
2009:
> Using the commands bellow I expected that the answer is TRUE, but it is
FALSE!
> 
> P_exposicao=.9
> (1-P_exposicao)==.1
Look at the difference of the two, it is much smaller than .Machine$double.eps
on my computer.

This is not a bug, it's due to the limited precision of floating point
numbers.

Sincerely
Olaf Mersmann