My Math Forum Chain code and neural networks

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August 13th, 2019, 06:16 AM   #1
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Chain code and neural networks

It is a brilliant introduction to NNs (rare to see a technical book so engaging to all ranges of abilities)...but I think there is a typo which is not in the online errata for the book.

See the attached image. I don't think the -2 in the last equation is correct, shouldn't it be simply 2?

It could be that the author has anticipated himself, because the error function derivative is actually taken away from the weights in the neural network. But as far as the maths go, should that be -2 or simply 2?

It could also be that I don't understand the chain code!
Attached Images
 Chain-code-nn.jpg (15.2 KB, 8 views)

 August 13th, 2019, 07:50 AM #2 Global Moderator   Joined: Dec 2006 Posts: 21,015 Thanks: 2250 Differentiating (1 - u)² = 1 - 2u + u² w.r.t. u gives -2 + 2u = -2(1 - u). Thanks from Owen Ransen
August 13th, 2019, 08:45 PM   #3
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Quote:
 Originally Posted by skipjack Differentiating (1 - u)² = 1 - 2u + u² w.r.t. u gives -2 + 2u = -2(1 - u).
That shows you how long it is that I have not done this stuff. Many thanks!

Owen

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