Course 1: Week 3 (Backpropagation derivative equations clarification)

Course Q&A Deep Learning Specialization Neural Networks and Deep Learning
1

Hi
Dear mentors/ fellows,
@ paulinpaloalto and @agpath

My question is related to Derivative Equations (Backpropagation Intuition),
I am confused about the dimension of dz[2] as it should be a row vector (1,m).
and how it is used to compute the dw[2] = dz[2] * a[1]T ?

as dz[2] – (1,m) dimensional row vector and
a[1] — (n[1],1) column vector
so how we could get dw[2] a column vector?

2

Hi @Tipu_Sherazi and welcome to the Specialization. Check your math regarding the dimensions of A1. As Prof Ng says in the videos, keeping track of the appropriate dimensions is seemingly straightforward, but often a source of broken algorithms. This is pencil and paper stuff.

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