[Limdep Nlogit List] nonlinear regression with restriction

[Michael Stobernack]

>Dear all,
>
>I would like to run the following nonlinear regression:
>
>Y = a1 + a2 * X +a3 * (1 - dk) * (b**2 - 2 * b * x + x**2) + u
>
>with dk = 1 if x <= b  and dk = 0 if x > b
>
>That is, there is a variable (dk) which depends on a parameter (b) 
>which itself
>is still to be estimated.
>
>The background is: I would like to get a linear regression between 
>x=0 and x=b,
>but a nonlinear regression for x>b. And I don't know the value of b 
>in advance.
>The regression should estimate the value of b.
>
>I would be very glad about any hints how to do this in Limdep.
>
>Best regards,
>
>Michael