How to plot contours for joint density of 2 independently distributed r.v.?

do you know the probability density functions for these random variable? 
If yes, then you need something like the following:

x <- seq(-5, 5, len = 50)
y <- seq(0.001, 10, len = 50)
z <- outer(x, y, function(x, y){
     dnorm(x) * dgamma(y, 5)
})

contour(x, y, z)

where you replace dnorm() and dgamma() with your pdf's.

If you just have a sample from X and Y, then you could use kernel 
density estimation, for instance, check

help("bkde2D", package = "KernSmooth")


I hope it helps.

Best,
Dimitris

X and Y are independently distributed random variables.
I would like to study the contours of the joint density of these two
variables.
Any function to call?

Thank you very much!

Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014