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annotate sigmoidGradient.m @ 9:8dd249e99b5b default tip

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Optimisations for backprop
author Jordi Gutiérrez Hermoso <jordigh@octave.org>
date Fri, 11 Nov 2011 20:36:02 -0500
parents 55430128adcd
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1 function g = sigmoidGradient(z)
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55430128adcd Implement sigmoidGradient.
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2 ##SIGMOIDGRADIENT returns the gradient of the sigmoid function
55430128adcd Implement sigmoidGradient.
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3 ##evaluated at z
55430128adcd Implement sigmoidGradient.
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4 ## g = SIGMOIDGRADIENT(z) computes the gradient of the sigmoid function
55430128adcd Implement sigmoidGradient.
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5 ## evaluated at z. This should work regardless if z is a matrix or a
55430128adcd Implement sigmoidGradient.
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6 ## vector. In particular, if z is a vector or matrix, you should return
55430128adcd Implement sigmoidGradient.
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7 ## the gradient for each element.
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395fc40248c3 Initial commit
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8
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55430128adcd Implement sigmoidGradient.
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9 s = @(z) 1./(1 + exp(-z));
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10 g = s(z).*(1 - s(z));
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395fc40248c3 Initial commit
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55430128adcd Implement sigmoidGradient.
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12 endfunction