choose
function
f
(
x
)
1
2
3
tangent
length
0
.
3
contours
1
step
11
-
1
.
0
-
0
.
5
0
.
0
0
.
5
1
.
0
-
1
.
0
-
0
.
5
0
.
0
0
.
5
1
.
0
x
y
