Before you post, please make sure to: Add a clear title Matrix size Confusion Add all required tags in the tag option (top-right of the post): dl-ai learning platform Shallow Neural Networks Write a detailed description of your issue. How is the size of the given matrix W is 4 by 3…

This may be a confusion on the weight matrix numbering. Looking just at the NN graphic: There is a W matrix that connects adjacent pair of layers. Each arrow on that graphic is a single real weight value. The W matrix between the inputs and the hidden layer, with all of the crossing arrows, that’…

So it would be right to say that W11 is a vector consisting of w1,1 , w1,2 , w1,3 and w1,4 , denoting all the wieghts coming out from the input x1 to all the four nodes in the first layer?

Matrix size confusion

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

paulinpaloalto January 21, 2026, 5:09am 4

This question has come up before. Here’s an ancient scroll that was recently excavated that is worth a look.

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Matrix size confusion

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