Displaying 3 results from an estimated 3 matches for "noncommutative".
2004 Sep 07
2
noncommutative addition: NA+NaN != NaN+NA
Hi guys.
Check this out:
> NaN +NA
[1] NaN
> NA + NaN
[1] NA
I thought "+" was commutative by definition. What's going on?
> R.version
_
platform powerpc-apple-darwin6.8
arch powerpc
os darwin6.8
system powerpc, darwin6.8
status
major 1
minor 9.0
year 2004
month 04
day 12
language R
>
(Both give NA under linux, so it looks
2009 Apr 30
2
NA_real_ <op> NaN -> NA or NaN, should we care?
On Linux when I compile R 2.10.0(devel) (src/main/arithmetic.c in
particular)
with gcc 3.4.5 using the flags -g -O2 I get noncommutative behavior when
adding NA and NaN:
> NA_real_ + NaN
[1] NaN
> NaN + NA_real_
[1] NA
If I compile src/main/arithmetic.c without optimization (just -g)
then both of those return NA.
On Windows, using a precompiled R 2.8.1 from CRAN I get
NA for both answers.
On Linux, after compilin...
2003 Nov 04
1
glm offset and interaction bugs (PR#4941)
...<- glm(seedlings ~ vegtype + burn01 + burn02 + offset(log(totalseeds)),
data = mydata, family = poisson)
summary(out)
So is is only partially bogus -- very dangerous for users that are less
than hyperalert.
The difference between out.barfu and out.ok shows that "+" in formulas
is noncommutative, which is very mind bending.
The regression in out.ok is o. k. It checks by hand.
For a more complete explanation (if more is wanted), including
the printout from these summary commands on my machine and the
check of out.ok "by hand", see
http://www.stat.umn.edu/geyer/5931/mle/seed...