aov-related segfault (PR#382)

[Prof Brian Ripley]

On Mon, 20 Dec 1999 pd@butterfly.kubism.ku.dk wrote:

> This crashes the development version, but apparently also earlier versions
> (a typo of course, but still shouldn't happen)
> 
> response<-rnorm(60)
> dag<-gl(3,2,60) 
> rep<-gl(2,1,60)
> person<-gl(10,6,60)
> aov(response~dag+Error(person/dag/response)) # error from model.matrix.default
> gc() # *poof*...


Progress report!

1) This is nothing specific to aov. It can be repoduced by

response <- rnorm(60)
dag <- gl(3,2,60) 
model.matrix(formula = response ~ dag/response)

2) The crash occurs because a 60x3 (rather than 60x6) matrix is allocated,
so lots of writing outside the matrix occurs.

3) model.matrix(~ dag + response:dag) works, but has a slightly different
terms structure.

4) S generates a 60x5 matrix, which looks wrong to me.


-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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