[R] poisson distribution

[David Winsemius]

On Sep 6, 2010, at 1:13 PM, tamas barjak wrote:

> Hello!
>
> I need some help.
> How I know it to draw the formula of the poisson distribution?
>
> expr<-expression(P(xi == k) == frac(lambda^k, factorial(k))*e^- 
> lambda) --->
> not good

?plotmath

(Do not see factorial as a plotmath "function"

Try:

expr<-expression(P(xi == k) == frac(lambda^k, k*"!")*e^-lambda)

>
> on the screen the " k! " not the Poisson Formula, but "factorial(k)"
>
> Thanx!

-- David.