$$f_y=e^{-[(A_y+\delta)/\gamma]^\delta}$$
I'm not sure how to I derive the least square method to solve the unknown parameter for delta and gamma. Any help would be appreciated.
What I did tried to do is to get along the line of bringing down the power of e using the ln function, and applied another ln function to the following equation after the first ln to bring down the delta. That's where I'm stuck at.