On Mon, Jul 19, 2010 at 9:09 AM, Wendy Han <wendyhan08@gmail.com> wrote:
> Hi,
>
> Excuse me for asking this silly question. But I really couldn't
understand
> why cov() and ccov() don't work for my calculation of covariance
matrix.
>
> a <- matrix(1:8, 2, 4)
> a
> [,1] [,2] [,3] [,4]
> [1,] 1 3 5 7
> [2,] 2 4 6 8
> > ccov(a)
> Error in solve.default(cov, ...) :
> Lapack routine dgesv: system is exactly singular
> I also tried colume bind, but it still doesn't work.
> > a1<- a[,1]
> > a2 <- a[,2]
> > a3<- a[,3]
> > a4 <- a[,4]
> > acomb <- cbind(a1,a2,a3,a4)
> > acomb
> a1 a2 a3 a4
> [1,] 1 3 5 7
> [2,] 2 4 6 8
> > ccov(acomb)
> Error in solve.default(cov, ...) :
> Lapack routine dgesv: system is exactly singular
> Yesterday, I used cov(), my function worked well. But today I ran the same
> code, it returned an error like:
>
> cov(td12)
> Error in solve.default(cov, ...) :
> system is computationally singular: reciprocal condition number >
1.97276e-24
> In addition: Warning message:
> 'cov' is deprecated.
> Use 'ccov' instead.
> See help("Deprecated")
> I don't know what is wrong, and I appreciate you kind help! Thank you!
>
> Wendy
>
>
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