problem with cov.* in package lqs

From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk]
On Wed, 24 Jan 2001, Liaw, Andy wrote:

I ran into an error message when I use the cov.* (rob, mcd, 

mve) function in

the package lqs.  The data matrix is 761 rows by 661 

columns.  I get the

following message:

	NA/NaN/Inf in foreign function call (arg 1)

Can anyone provide some insight on why this occurs, and 

better yet, how to

get around it?

Not without more information.  But that is probably in

        z <- .C("mve_fitlots", as.double(x), as.integer(n), 
as.integer(p),

in which case it probably means some column has IQR 0.

Generally, you need to help yourself on these things.

1) traceback() tells you where the error is.
2) debug(cov.rob) and re-run the call, and step though a line 
at a time
In particular, look at divisor.