[R] Propositions to fit a 2 pieces function

[Eric Rodriguez]

Hi,

I would like to have some advices about how to fit such function:

f(x) =  a.x^b                      if x <= t
          c.x - c.t + a.t^b       otherwise

I have to minimize the least-squares error  knowing x and f(x).

Do you have any propositions of what should I use to achieve it ?

Thanks a lot !

Eric