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Old 05-07-2012, 03:43 AM
rohanag rohanag is offline
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Default clarification on lecture 9

I have a slight problem with delta_E_in in slide 23 of lecture 9.



I think there should be a negative sign in the exponentiation term,
e^(y_n * w.transpose * x_n) should be e^( - y_n * w.transpose * x_n )

as it would result from differentiating the cross entropy error? Please clarify.



Thank you
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Old 05-07-2012, 04:13 AM
IamMrBB IamMrBB is offline
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Default Re: clarification on lecture 9

The formula on the slide is correct.

d/dx (ln(1+exp(-f(x))) = -exp(-f(x))f'(x)/(1+exp(-f(x))

now multiply both numerator and denominator with exp(f(x)) and the right formula -f'(x)/(exp(f(x))+1) follows since exp(f(x))*exp(-f(x)) = 1
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Old 05-07-2012, 04:33 AM
rohanag rohanag is offline
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Default Re: clarification on lecture 9

got it, thanks
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cross entropy error, doubt, gradient, lecture 9

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