Back Propagation $(10)$

Consider the following function of $x=(x_1,x_2,x_3)$ :

$f(x)=(2(x_1^2-(2x_2^3+x_3))+\frac{1}{2})$

where $$ is the sigmoid function

$(x)=\frac{1}{1+e^{-x}}$

Evaluate $f(x)$ at widehat$(x)=(1,0\mathrm{.}5,-1).$ Then, compute the gradient $gra{d}_{x}f(x)$ and evaluate it at the same

point.