Error about initialize_parameters_deep in Week4 assignment 1

You’re missing an operator here:

Thank you TMosh,
The issue has been fixed but second test is failed can you advice please:

The transposes are wrong in the first term with the np.dot. I thought we had already covered that issue earlier on this thread. In order to understand the point, please read what I said and also it is essential that you follow the link I gave in that earlier post and understand the points that are made on that other thread.

Hi @paulinpaloalto
i have read the earlier thread, and as per my understood you can Transpose Y with dot product and keep np.sum. OR Transpose A then no need for np.sum .Which option is the correct ?Please your support the image is not clear :frowning:

Please read this post. It is not correct to transpose Y. That post demonstrates why that is wrong and why it matters which argument you transpose.

That post gives a very concrete demonstration by doing the computation both ways and showing that the answers are different.

Hi @paulinpaloalto

I read this article again, and i have been transposed AL instead Y as per you recommendation but still not fix second test and keep failed PFB:

The cost should be a scalar or a 1 x 1 np array, but yours is a 3 x 3 array. So you must be doing something wrong. In your previous version, you had two terms: the Y = 1 term, which you did with dot products and the Y = 0 term, which you did with elementwise multiply followed by np.sum. In the elementwise version, you don’t need any transposes, right?

My recommendation (which I also made earlier in this thread) is that you be consistent and use the same coding with both the Y = 1 and Y = 0 terms.

1 Like

Observations:
If you have two vectors, with sizes (1 x K) and (K x 1).
Then, there are two possible dot products:

  • (1 x K) \cdot (K x 1) gives a (1 x 1) result (a scalar).
  • (K x 1) \cdot (1 x K) gives a (K x K) matrix result.
1 Like

Salam @paulinpaloalto ,

Thank you for your effort and solved my problem by make the calculations on paper/Pencil .

Salam @TMosh ,

Thank you for your observations it was really good hint .