it means that the matrix w is singular; check
all.equal(w[, 1], w[, 4])
all.equal(w[, 2], w[, 3])
# or
qr(w)$rank
you need linearly independent columns!
I hope it helps.
Best,
Dimitris
----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm
----- Original Message -----
From: "Sam R. Smith" <samrobertsmith at yahoo.com>
To: <r-help at stat.math.ethz.ch>
Sent: Friday, October 28, 2005 9:06 AM
Subject: [R] solve error
>> w
> [,1] [,2] [,3] [,4]
> 1:1 0.0 0.5 0.5 0.0
> 2:1 0.5 0.0 0.0 0.5
> 1:2 0.5 0.0 0.0 0.5
> 2:2 0.0 0.5 0.5 0.0
>
>> solve(w)
> Error in solve.default(w) : Lapack routine dgesv:
> system is exactly singular
>
> what does the error mean?
>
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