[Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread jan . hattendorf 
Full_Name: jan hattendorf
Version: 2.9.0
OS: XP
Submission from: (NULL) (213.3.108.185)


I get an incorrect result for

(41/10-1/10)%%1

[1] 1

The error did not occur with other numbers than 41 (1, 11, 21, 31, 51, ...)


test - rep(NA, 1000)
for(i in 1:1000){
  test[i] - i/10-1/10
}
test[test%%1==0]

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Re: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread Peter Dalgaard 
jan.hattend...@unibas.ch wrote:
 Full_Name: jan hattendorf
 Version: 2.9.0
 OS: XP
 Submission from: (NULL) (213.3.108.185)
 
 
 I get an incorrect result for
 
 (41/10-1/10)%%1
 
 [1] 1
 
 The error did not occur with other numbers than 41 (1, 11, 21, 31, 51, ...)
 
 
 test - rep(NA, 1000)
 for(i in 1:1000){
   test[i] - i/10-1/10
 }
 test[test%%1==0]
 
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FAQ 7.31

-- 
   O__   Peter Dalgaard Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark  Ph:  (+45) 35327918
~~ - (p.dalga...@biostat.ku.dk)  FAX: (+45) 35327907

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Re: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread Achim Zeileis 

Not a bug, just a FAQ (7.31).
http://CRAN.R-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f

On Sat, 1 Aug 2009, jan.hattend...@unibas.ch wrote:


Full_Name: jan hattendorf
Version: 2.9.0
OS: XP
Submission from: (NULL) (213.3.108.185)


I get an incorrect result for

(41/10-1/10)%%1

[1] 1

The error did not occur with other numbers than 41 (1, 11, 21, 31, 51, ...)


test - rep(NA, 1000)
for(i in 1:1000){
 test[i] - i/10-1/10
}
test[test%%1==0]

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Re: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread ONKELINX, Thierry 
This is not a bug. It is a case of R FAQ 7.34:
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-the
se-numbers-are-equal_003f 




ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
thierry.onkel...@inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

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

-Oorspronkelijk bericht-
Van: r-devel-boun...@r-project.org
[mailto:r-devel-boun...@r-project.org] Namens jan.hattend...@unibas.ch
Verzonden: zaterdag 1 augustus 2009 22:05
Aan: r-de...@stat.math.ethz.ch
CC: r-b...@r-project.org
Onderwerp: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

Full_Name: jan hattendorf
Version: 2.9.0
OS: XP
Submission from: (NULL) (213.3.108.185)


I get an incorrect result for

(41/10-1/10)%%1

[1] 1

The error did not occur with other numbers than 41 (1, 11, 21, 31, 51,
...)


test - rep(NA, 1000)
for(i in 1:1000){
  test[i] - i/10-1/10
}
test[test%%1==0]

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Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer 
en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is
door een geldig ondertekend document. The views expressed in  this message 
and any annex are purely those of the writer and may not be regarded as stating 
an official position of INBO, as long as the message is not confirmed by a duly 
signed document.

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Re: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread Sean O'Riordain 
Good morning Jan,

Could this be covered off by the following?

http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f

Kind regards,
Sean

On Sat, Aug 1, 2009 at 9:05 PM, jan.hattend...@unibas.ch wrote:
 Full_Name: jan hattendorf
 Version: 2.9.0
 OS: XP
 Submission from: (NULL) (213.3.108.185)


 I get an incorrect result for

 (41/10-1/10)%%1

 [1] 1

 The error did not occur with other numbers than 41 (1, 11, 21, 31, 51, ...)


 test - rep(NA, 1000)
 for(i in 1:1000){
  test[i] - i/10-1/10
 }
 test[test%%1==0]

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Re: [Rd] incorrect result (41/10-1/10)%%1 (PR#13863)

2009-08-03 Thread Petr Savicky 
 I get an incorrect result for
 
 (41/10-1/10)%%1
 
 [1] 1

Note that due to rounding errors, 41/10-1/10 is
  formatC(41/10-1/10, digits=20) # [1] 3.9995559

Besides FAQ 7.31, related information may be found also at
  http://wiki.r-project.org/rwiki/doku.php?id=misc:r_accuracy

Petr.

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