Tal Galili wrote:
(I use R 2.9.1 with win XP)
If I run this code:
seq(-0.1,.9, by = .05)[seq(-0.1,.9, by = .05) <= 0.5]
I get this output:
[1] -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45
Why is 0.50 not in the results ?
(It seems that it gives a slightly bigger number then 0.5 but I don't
understand why it does that)
Where as if I try:
seq(-0.1,.9, by = .05)[seq(-0.1,.9, by = .05) <= 0.4]
and get:
[1] -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Then 0.40 WILL be in the results.
Neither a bug nor a feature, just the way things are. None of -0.1, 0.9
or 0.05 are numbers that can be represented exactly in R, so it's not
too surprising that when you add a dozen copies of the last one to the
first one, you don't get exactly 0.5 (which, being a power of 2, is
exactly representable. See FAQ 7.31.
Duncan Murdoch
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