4 messages · Alexandre Courtiol, Peter Dalgaard, John Nolan +1 more
Full_Name: alex Version: 2.8.1 OS: Ubuntu / MacOSX Submission from: (NULL) (162.38.183.51)
0.6==0.6
[1] TRUE
seq(0,1,0.1)==0.4
[1] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.6
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.8
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE What is wrong with 0.6 ??? (TRUE is missing) I tried 3 differents computers (2 Ubuntu with R 2.8.1, and one Mac with R 2.8).
0.6==0.6
[1] TRUE
seq(0,1,0.1)==0.4
[1] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.6
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.8
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE What is wrong with 0.6 ??? (TRUE is missing) I tried 3 differents computers (2 Ubuntu with R 2.8.1, and one Mac with R 2.8).
FAQ 7.31, not a bug. Expect about 10 people to tell you so.
O__ ---- Peter Dalgaard ?ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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seq(0,1,0.1)==0.4
[1] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.6
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
seq(0,1,0.1)==0.8
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE What is wrong with 0.6 ??? (TRUE is missing) I tried 3 differents computers (2 Ubuntu with R 2.8.1, and one Mac with R 2.8).
If you know that all the numbers in a sequence should have a given decimal
precision, then you obtain a better result using round(,digits=...).
For example,
x <- round(seq(0,1,0.1), digits=1)
rbind(x == 0.4, x == 0.6, x ==0.8)
produces
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11]
[1,] FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE FALSE FALSE
[2,] FALSE FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE FALSE FALSE
[3,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE TRUE FALSE FALSE
This does not mean, that x[7] is now equal to 0.6, however both x[7] and 0.6
are represented by the same 53-bit floating point number
formatC(x[7], digits=20) # "0.5999999999999999778"
formatC(0.6, digits=20) # "0.5999999999999999778"
Petr.