[R] Matrix Multiplication, Floating-Point, etc.
Charles C. Berry
cberry at tajo.ucsd.edu
Mon Jul 30 18:27:42 CEST 2007
7.31 Why doesn't R think these numbers are equal?
On Fri, 27 Jul 2007, Talbot Katz wrote:
> I recently tried the following in R 2.5.1 on Windows XP:
> [1,] -2.664427e-17
>  0
> (I got the same result with R 2.4.1 on a different Windows XP machine.)
> I expect this issue is very familiar and probably has been discussed in this
> forum before. Can someone please point me to some documentation or
> discussion about this? Is there some standard way to get the "correct"
> answer from %*%?
> -- TMK --
> 212-460-5430 home
> 917-656-5351 cell
> R-help at stat.math.ethz.ch mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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