Message-ID: <x2ekj8itle.fsf@biostat.ku.dk>
Date: 2004-11-05T08:32:45Z
From: Peter Dalgaard
Subject: Covariance bug in R-1.8.0
In-Reply-To: <46334.217.229.7.13.1099626816.squirrel@217.229.7.13>
lederer at trium.de writes:
> R-1.8.0 seems to calculate wrong covariances, when the argument of cov()
> is a matrix or a data frame.
> The following should produce a matrix of zeroes and NaNs:
...
> Under 1.9.1 (Linux) and 1.9.0 (Windows) i get the expected matrix of
> zeroes and NaNs.
>
> This example is not very special. Under R-1.8.0 cov produced wrong result
> for any random matrix i tried.
Presumably, this is the same as PR#4646.
> Doesn't this mean, that *any* result obtained under R 1.8.0 is unreliable?
It means that covariances and correlations are sometimes computed
incorrectly.
> By the way, i just recompiled R-1.8.0 from source under Linux and tried
> 'make check'. All tests were ok.
Yes. We don't release versions that don't pass their own tests.
> Does there exist a more detailed set of tests, which could insure that
> at least the most basic R functions work correctly?
We add regression tests as we discover and fix bugs. We can't fix old
versions retroactively though, we release patch versions (e.g. 1.8.1)
instead.
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907