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sigmoid function and derivative

On Tue, Jun 26, 2018 at 8:26 PM, Sharan Basappa <sharan.basappa at gmail.com>

> 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)

The derivative tells you what direction to go in, as you update your
coefficients. It's a slope of a curve.  Otherwise, you'd be steering blind.