sigmoid function and derivative
Terry Reedy
tjreedy at udel.edu
Wed Jun 27 01:40:00 EDT 2018
On 6/26/2018 11:26 PM, Sharan Basappa wrote:
> Folks,
>
> I know this is not a machine learning forum but I wanted to see if anyone can explain this to me.
>
> In artificial neural network, I can understand why sigmoid is used but I see that derivative of sigmoid output function is used. I am not able to understand why.
>
> For example:
> # convert output of sigmoid function to its derivative
> def sigmoid_output_to_derivative(output):
> return output*(1-output)
Derivatives are used for backpropagation* of errors for adjusting
weights. The convenient form of sigmoid derivative is a reason to use
sigmoids as transfer functions.
* You can look backpropagation as a method of training.
--
Terry Jan Reedy
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