Thread: Problem 3.7d
View Single Post
  #4  
Old 10-14-2012, 06:00 AM
magdon's Avatar
magdon magdon is offline
RPI
 
Join Date: Aug 2009
Location: Troy, NY, USA.
Posts: 595
Default Re: Problem 3.7d

In gradient descent we studied a similar problem: find the direction to move to minimize the error the most for a given step size. This direction was the negative gradient of E. You can use that fact to solve part (b), because the gradient approximation is exact for linear functions.

Part (a) defined a function \hat E_1. If you set (u,v)=(0,0), \hat E_1 becomes a function of \Delta u,\Delta v. You want to minimize this function under the constraint that \|(\Delta u,\Delta v\|=0.5.

If you choose to use the gradient hint, the gradient of E_1 is related to the coefficients a_u,a_v defined in part (a).

Quote:
Originally Posted by mileschen View Post
Could you possibly redescribe the Problem 3.17b for me? I don't quite understand the requirements of this question. What's the relation between it and the gradient descent algorithm for logistic regression of the textbook?
__________________
Have faith in probability
Reply With Quote