seq results compare with vector return false

Question

I have the following code:

     seq(0.2, 0.4, by = 0.1) == c(0.2, 0.3, 0.4)

which yields:

     [1]  TRUE FALSE  TRUE

Could somebody please explain this result?

You should read the R-FAQ.This is in section 7. – IRTFM Jul 20 '15 at 17:48 — IRTFM, Jul 20 '15 at 17:48

score 1 · Accepted Answer · answered Jul 20 '15 at 17:37

This is numerical error:

> seq(0.2, 0.4, by = 0.1)-c(0.2, 0.3, 0.4)
[1] 0.000000e+00 5.551115e-17 0.000000e+00

See ?identical or ?all.equal and compare:

> identical(seq(0.2, 0.4, by = 0.1),c(0.2, 0.3, 0.4))
[1] FALSE
> all.equal(seq(0.2, 0.4, by = 0.1),c(0.2, 0.3, 0.4))
[1] TRUE

Also compare:

> seq(2L,4L,by=1L)/10==c(.2,.3,.4)
[1] TRUE TRUE TRUE

1 Answers1