[R] Generating random geographical coordinates

[Poizot Emmanuel]

Dear all,

I have two coordinates vectors, say X and Y of length n.
I want to generate for each couple of coordinates X1,Y1 X2,Y2 
X3,Y3....Xn,Yn a random coordinate which is located in a square define 
as X +/- dx and Y +/- dy.
I saw the runif function which can generate for just one value at a time 
what I want  : runif(1, X - dx, X + dx) for X and runif(1, Y - dy, Y + 
dy) for Y.
I would like to know if there is not a more powerfull way in R to 
generate directly the set of random coordinates.
Regards

-- 
Emmanuel Poizot