WOLFRAM
|
DEMONSTRATIONS PROJECT
Directional Derivatives
f
(
x
,
y
)
=
-
2
x
-
2
y
+
4
∇
f
(
0
,
0
)
=
(
0
,
0
)
|
|
∇
f
(
0
,
0
)
|
|
=
0
D
u
f
(
0
,
0
)
=
0
s
n
a
p
t
o
g
r
i
d
s
h
o
w
g
r
a
d
i
e
n
t
∇
f
s
h
o
w
u
n
i
t
d
i
r
e
c
t
i
o
n
v
e
c
t
o
r
u
U
s
e
t
h
e
v
e
c
t
o
r
a
n
d
p
o
i
n
t
c
o
n
t
r
o
l
s
(
a
r
r
o
w
s
)
i
n
t
h
e
t
o
p
p
a
n
e
t
o
a
d
j
u
s
t
t
h
e
l
o
c
a
t
i
o
n
a
n
d
a
n
g
l
e
o
f
t
h
e
d
i
r
e
c
t
i
o
n
v
e
c
t
o
r
o
n
t
h
e
s
u
r
f
a
c
e
.
