# [R] [] for R

Vitalie S. vitosmail at rambler.ru
Tue Aug 25 12:00:55 CEST 2009

```see ?[

For '['-indexing only: 'i, j, ...' can be logical vectors,
indicating elements/slices to select.  Such vectors are
recycled if necessary to match the corresponding extent.  'i,
j, ...' can also be negative integers, indicating
elements/slices to leave out of the selection.

so 1+xi*xx>0 is a logical vector.

On Mon, 24 Aug 2009 17:33:36 +0200, kfcnhl <zhengchenji18 at hotmail.com>
wrote:

>
> I am assuming the variable out is the output parameter.
> However, I don't understand what is  out[1+xi*xx>0]?
> Can someone explain this to me?
>
> Chen
>
>
> dGEV <- function(x, xi, mu = 0, sigma = 1, logvalue=FALSE)
>   {
>     xx <- (x-mu)/sigma
>     #use the new dGumbel which passes mu and sigma:
>     #if (xi==0) out <- dGumbel(xx,logvalue=TRUE)-log(sigma)
>     if (xi==0) {
>        return(out <- dGumbel(x, mu, sigma, logvalue));
>     }
>
>     else
>       { out <- rep(-Inf,length(x))
>         out[1+xi*xx>0] <- (-1/xi-1)*log(1+xi*xx[1+xi*xx>0]) -
> (1+xi*xx[1+xi*xx>0])^(-1/xi) -log(sigma)
>       }
>     if (!(logvalue))
>       out <- exp(out)
>     out
>   }

--

```