[R] Solving Matrices
Douglas Bates
bates at stat.wisc.edu
Thu Apr 15 15:19:49 CEST 2004
wettenhall at wehi.EDU.AU writes:
> On April 15th, Elizabeth wrote:
> <snip>
> > In execises 39-42, determine if the columns of the matrix span
> > R4:
> <snip>
> >(or x <- matrix(data=c(7, -5, 6, -7, 2, -3, 10, 9, -5,
> > 4, -2, 2, 8, -9, 7, 15), nrow=4, ncol=4)
> >
> >That is the whole of the question <snip>
>
> Have you tried det(x) and/or eigen(x) ?
An alternative is to determine the condition number (kappa) of the
matrix
> x <- matrix(data=c(7, -5, 6, -7, 2, -3, 10, 9, -5,
+ 4, -2, 2, 8, -9, 7, 15), nrow=4, ncol=4)
> kappa(x)
[1] 5.31557e+17
A very large condition number like this indicates that the matrix is
computationally singular.
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