I'm looking on a given solution of the first assignment of cs231n course.
Down below a snippet from the loss function.
I don't really understand lines 140-143
. Can you explain why dscores
(the derivative of scores
) is calculated like that?
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Sign up to join this communityI'm looking on a given solution of the first assignment of cs231n course.
Down below a snippet from the loss function.
I don't really understand lines 140-143
. Can you explain why dscores
(the derivative of scores
) is calculated like that?
Be aware that posting code in images very annoying to copy/paste and it's bad for web reference ment.
This is due to the derivative of the softmax, but to me it's seems fishy.
If $S$ is the softmax vector, then the Jacobian $DS$ consists of $S_j(\delta_{ij}-S_i)$. This could explain the -=1
part, but not the /=N
, and not the shape either.
y
? andN
in conjunction tolim_scores
? $\endgroup$ – Matthieu Brucher Dec 22 '18 at 21:04