[Rd] eigen returns NAs from a real matrix

[Prof Brian Ripley]

On Sat, 17 Mar 2007, Spencer Graves wrote:

> Hi, All:
>     Attached please find a symmetric, indefinite matrix for which 
> 'eigen(...)$vectors' included NAs: 
>> load("eigenBug.Rdata")
>> sum(is.na(eigen(eigenBug)$vectors))
> [1] 5670
>> sessioninfo()
> Error: could not find function "sessioninfo"
>> sessionInfo()
> R version 2.4.1 (2006-12-18)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=English_United States.1252;LC_CTYPE=English_United 
> States.1252;LC_MONETARY=English_United 
> States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
>
> attached base packages:
> [1] "stats"     "graphics"  "grDevices" "utils"     "datasets"  "methods" [7] 
> "base"
>     Using EISPACK does NOT return NAs: > sum(is.na(eigen(eigenBug, 
> EISPACK=TRUE)$vectors))
> [1] 0
>
>
>     I traced the problem to the following line in 'eigen':
>           z <- if (!complex.x)
>               .Call("La_rs", x, only.values, PACKAGE = "base")
>
>
>     Comments?

Nothing appeared as an attachment.

-- 
Brian D. Ripley,                  ripley at 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