On 22.06.2017 17:11, Bernd Funovits wrote:
Hello,
I experienced some unexpected behaviour while determining the rank of
matrices (sometimes 1x1 matrices):
base::qr(matrix(1e-20))$rank returns 1 (incorrect)
base::qr(diag(c(1, 1e-20)))$rank returns 2 (incorrect)
Why do you believe this is incorrect?
0 != 1e-20
and 1e-20 is well representable without significant rounding errors given
> .Machine$double.xmin
[1] 2.225074e-308
Best,
Uwe Ligges
Best regards,
Bernd
> R.version
_
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 4.0
year 2017
month 04
day 21
svn rev 72570
language R
version.string R version 3.4.0 (2017-04-21)
nickname You Stupid Darkness
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