Week 3 Programming Assignment Exercise 7 subtract AND operator -= update parameter

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

Hi, for the General gradient descent rule, may I know why must we do

W1 = W1 - learning_rate * dW1

when I try with

W1 -= (learning_rate * dW1)

it returns me with an error of

Error: Wrong output for variable W1

as far as I know, the 2 lines above have the same meaning, but in the programming assignment I got an error when using -= . Can you clarify on this matter or i might have missed something? thank you so much.

2

It turns out that those two lines result in the same output value, but they are not equivalent in terms of how they handle memory. Here’s a thread which explains why -= does not work for this particular test case unless you take some additional action.

3

I understand now, thank you so much for it!!!

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