Let
�
(
�
)
f(w) be a function of vector
�
w, i.e.

�
(
�
)
=
1
1
+
e
−
�
�
�
.
f(w)=
1+e
−w
T
x

1
​
.

Determine the first derivative and matrix of second derivatives of
�
f with respect to
�
w.