R help - Dec 2009 - how to calculate covariance matrix in R? why cov doesn't work

Hello, 

Sorry. It may be a stupid question. 
I have two vectors
a<-c(9,3,5)
b<-c(3,4,1)
How can I get the variance-covariance matrix of these two vectors?
I tried cov(a,b), I got a number not a matrix.
I tried to transpose vector a and b as t(a) and t(b), it still cannot work.

Any suggestions? Thank a lot!
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Try this:

a <- c(9,3,5)
b<-c(3,4,1)
cbind(a, b)
#     a b
# [1,] 9 3
# [2,] 3 4
# [3,] 5 1

cov(cbind(a, b))
#           a          b
# a  9.3333333 -0.6666667
# b -0.6666667  2.3333333

HTH,
Jorge

On Thu, Dec 3, 2009 at 11:29 PM, aegea <> wrote:
>
> Hello,
>
> Sorry. It may be a stupid question.
> I have two vectors
> a<-c(9,3,5)
> b<-c(3,4,1)
> How can I get the variance-covariance matrix of these two vectors?
> I tried cov(a,b), I got a number not a matrix.
> I tried to transpose vector a and b as t(a) and t(b), it still cannot work.
>
> Any suggestions? Thank a lot!
> --
> View this message in context:
>
http://n4.nabble.com/how-to-calculate-covariance-matrix-in-R-why-cov-doesn-t-work-tp948253p948253.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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