Regression with exponential weights

[Zain Mian]

Hi,

Could someone please guide on how to perform the following regression in STATA:

Y = b*e^-0*X_t-1 + b*e^-a*X_t-2 + b*e^-a2*X_t-3 + e

I need the estimates for both b and a. Thank you.

[Carlo Lazzaro]

Zain:
see -help nl-.