From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>

Date: Fri 05 Nov 2004 - 16:57:56 EST

Date: Fri 05 Nov 2004 - 16:57:56 EST

Please do read the posting guide and the FAQ. E.g. the posting guide says

Common posting mistakes:

...

Finding a bug in an old version of R that has been fixed in the most
recent version.

This was a bug in 1.8.0, but the current version of R is 2.0.0 with 2.0.1 in beta test. We can't fix bugs retrospectively.

If you take a look at the `bugs fixed' lists since 1.8.0 you will think you were remiss not to have upgrade a long time ago.

On Fri, 5 Nov 2004 christianlederer@t-online.de wrote:

> Full_Name: Christian Lederer

*> Version: 1.8.0
**> OS: Linux
**> Submission from: (NULL) (217.229.7.13)
**>
**>
**> 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:
*

Actually of zeroes and NAs, and it does in current R.

*> x <- matrix(c(NA ,NA ,0.9068995 ,NA ,-0.3116229,
*

> -0.06011117 ,0.7310134 ,NA ,1.738362 ,0.6276125,

*> 0.6615581 ,NA ,NA ,-2.646011 ,-2.126105,
**> NA ,1.081825 ,NA ,1.253795 ,1.520708,
**> 0.2822814 ,NA ,NA ,NA ,NA,
**> 0.03291028 ,NA ,NA ,NA ,NA,
**> NA ,NA ,NA ,-0.5462126 ,-0.1997394,
**> NA ,-0.3419413 ,-0.2675226 ,-1.000133 ,-0.1346234,
**> NA ,NA ,-0.411743 ,1.301612 ,NA,
**> 0.922197 ,NA ,0.9513522 ,0.2357021 ,NA),
**> nrow=10, ncol=5)
**>
**> c1 <- cov(x, use="pairwise.complete")
**>
**> c2 <- matrix(nrow=5, ncol=5)
**> for (i in 1:5)
**> {
**> for (j in 1:5)
**> {
**> c2[i,j] <- cov(x[,i], x[,j], use="pairwise.complete")
**> }
**> }
**>
**> c2-c1
**>
**> Instead, R-1.8.0 produces this result:
**>
**> [,1] [,2] [,3] [,4] [,5]
**> [1,] 0.00000000 -0.03053828 NA -0.0144996353 -0.03485883
**> [2,] -0.03053828 -0.01649857 NA 0.0137259383 -0.02960707
**> [3,] NA NA -0.1296134 NA NA
**> [4,] -0.01449964 0.01372594 NA -0.0003152629 0.08717648
**> [5,] -0.03485883 -0.02960707 NA 0.0871764791 0.04961190
**>
**> This happens as well under Linux (Suse 9.1) as well as under Windows NT.
**>
**> 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.
**>
**> Doesn't this mean, that *any* result obtained under R 1.8.0 is unreliable?
*

>From cov(x, use="pairwise.complete"), yes. But that is a very unusual usage.

> By the way, i just recompiled R-1.8.0 from source under Linux and tried

*> 'make check'. All tests were ok.
**> Does there exist a more detailed set of tests, which could insure that
**> at least the most basic R functions work correctly?
*

This is not a `most basic R function'. Look in the test directory in the sources to see that we do have an extensive series of tests.

-- Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-develReceived on Fri Nov 05 17:04:51 2004

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