Incorrect Formulas in Theory

[XiaoPeng0x3]

Description

Hello, I think you've accidentally written a wrong formula. The derivative of sigmoid function is $\frac{d}{dx}\sigma(x) = \sigma(x)(1 - \sigma(x))$ and you written it as $\sigma(x) - (1-\sigma(x))$ . Its not a big deal but confuse me :-). Have a good day.