It is not clear that you have read the help page that arise with:
?Inf
"Note:
In R, basically all mathematical functions (including basic
Arithmetic), are supposed to work properly with +/- Inf and NaN as
input or output.
The basic rule should be that calls and relations with Infs really are
statements with a proper mathematical limit."
Also:
> Inf+Inf
[1] Inf
> Inf-Inf
[1] NaN
> -2/0
[1] -Inf
> Inf*Inf
[1] Inf
> Inf*(-Inf)
[1] -Inf
On Aug 29, 2009, at 9:58 PM, Michael Hannon wrote:
Greetings. I somehow had the impression that an infinite number, as
obtained by dividing by zero, for instance, would be flagged as both
missing ("NA") and not a number ("NaN"). It appears that I was
wrong on both counts, although the is.finite function correctly
returns FALSE in such a case. Please see the appended for some
details. I guess that the bottom line is that R works the way it
works, but if you can add anything that will further instruct me,
I'd appreciate it.
So I suppose the obvious further instruction is to read the help pages.
Thanks.
-- Mike
y <- 2/0
y
[1] Inf
is.na(y)
[1] FALSE
is.nan(y)
[1] FALSE
is.finite(y)
[1] FALSE
z <- log(-1)
Warning message:
In log(-1) : NaNs produced
z
[1] NaN
is.nan(z)
[1] TRUE
is.na(z)
[1] TRUE
-----
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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