R help - Oct 2007 - Multivariate chi-square distribution function

Dear All,

Is there any function in R for computing "multivariate chi-square  
distribution"?
How about "multivariate gamma distribution"?
I appreciate any comment on this subject.

Thank you,

Amin Zollanvari
PhD student
Department of Electrical and Computer Engineering,
Texas A&M University,
College Station, TX

Hello


If you want the multivariate t-distribution,
use rmvt() of the mvtnorm package.

If you want the Wishart distribution, one
can write a little nonce function:

library(mvtnorm)

rwis <- function(n,sigma){
crossprod(rmvnorm(n,sigma=sigma))
}

I'm not sure what you mean by the multivariate gamma
distribution, but a good candidate might be the
Dirichlet.  This is implemented in several packages;
see ?rdiric of the VGAM package for one example.


HTH


rksh



On 9 Oct 2007, at 18:39, aminzoll at ece.tamu.edu wrote:
> Dear All,
>
> Is there any function in R for computing "multivariate chi-square
> distribution"?
> How about "multivariate gamma distribution"?
> I appreciate any comment on this subject.
>
> Thank you,
>
> Amin Zollanvari
> PhD student
> Department of Electrical and Computer Engineering,
> Texas A&M University,
> College Station, TX
>
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