* element-wise operation in dZ[l]


I have been trying to calculate dz[1] manually and I got this expression: dz[2] x dw[2] x g[1]'(z[1]). However, I do not really understand where the element-wise operation (*) comes from. If anyone could help me, I would appreciate it.

Thanks in advance.

Hello Julio,

is this related to any assignment in particular?

Can you please mention the week and assignment name you are working on?



This issue appears in week 3, in the explanation of backward propagation.

Do you have an understanding about what element-wise operation is?

Yes, I understand that the element-wise product consists in multipliying each element without adding later. But I do not really understand why the operation is element-wise and not a dot product.