[R] defining a function by branches

[Pedro Rodrigues de Almeida]

Hi there,

How can I plot a function in R which is defined by conditional 
branches?, e.g.:

u(x) = 1, Ed<x<2Ed (where Ed is a positive constant, say, 25);
u(x)=0.5*x, x>2Ed

curve(u(x), ....)

So far I have had to use curve(..., add=TRUE) with two function define 
by segments, i.e., two branches or intervals for the variable x, say, 
25,50 and then from 50,... and I would appreciate a more elegant 
solution if possible.

Thanks a lot,

Pedro Rodrigues de Almeida
Helsinki - Finland