Possible error Lecture 9 - NN3 slide 9/17

Possible error Lecture 9 - NN3 slide 9/17

by ALESSANDRO RESTA -
Number of replies: 3

Hi,

there might be an error in the step 4 of the most internal loop of slide 9 lecture 9:

w_sq ← w_sq + ηΔw_sq

should be:

w_sq ← w_sq - ηΔw_sq

because we want to go to the opposite direction of the derivative

In reply to ALESSANDRO RESTA

Ri: Possible error Lecture 9 - NN3 slide 9/17

by RICCARDO CAPPI -
Hi!
I might be wrong but i think the slide is correct.
Δw_sq is equal to the following expression:
delta_w
As you can see there is a minus at the beginning of the expression. 
So w_sq ← w_sq - η(-Δw_sq) is equal to w_sq ← w_sq + ηΔw_sq


In reply to RICCARDO CAPPI

Ri: Possible error Lecture 9 - NN3 slide 9/17

by ALESSANDRO RESTA -
Hi,
thanks for the response.
I'm not convinced, since the minus comes out from the derivation process, so Δw_sq, which is the derivative, contains the minus already.
-Δw_sq is not the derivative anymore, it is the opposite (we are changing its sign).