[R] Error message - what does it mean???

[Prof Brian Ripley]

On Tue, 9 Mar 2004, Monica Palaseanu-Lovejoy wrote:

> Hi,
> 
> I am trying to calculate mahalanobis distances for a matrix x with 
> n*p variables. I am getting the following error:
> 
> md2 <- mahalanobis(x, center, cov)
> Error in solve.default(cov, tol = tol.inv) : 
>         system is computationally singular: reciprocal condition 
> number = 2.11165e-009
> 
> What does it means?

Error messages usually mean what they say, and it hard to see what you
mind to understand here.  Whatever you supplied for `cov' is a singular
matrix to the default tolerance, described on the help page.  If you know 
what is going on with your data, you could reduce the argument `tol.inv'.

-- 
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