I had a question from a SparseM user this morning who wanted to do
something
like this: (his dimensions, my data)
require(SparseM)
ia <- sample(1:52993,351718,replace=TRUE)
ja <- sample(1:52993,351718,replace=TRUE)
ra <- rnorm(351718)
dim <- as.integer(rep(52993,2))
A <- new("matrix.coo",ra=ra,ia=ia,ja=ja,dim=dim)
The last step failed because validity checking for objects of class
matrix.coo
wanted to test whether length(ra) > prod(dim), but unfortunately I'd
implemented
the test as nrow*ncol and both were integers of size 52993 so the
product
produced an integer overflow. I see in R-help that there was some
discussion
of this sort of thing with sum() and it appears that perhaps prod was
also adapted
to avoid this problem. I'm just wondering whether there was some more
general
lesson to be learned here. Other than the well-known "expect the
unexpected."
url: www.econ.uiuc.edu/~roger Roger Koenker
email rkoenker@uiuc.edu Department of Economics
vox: 217-333-4558 University of Illinois
fax: 217-244-6678 Champaign, IL 61820
