g
r
a
p
h
J
a
c
o
b
i
a
n
e
l
l
i
p
t
i
c
f
u
n
c
t
i
o
n
s
S
e
i
f
f
e
r
t
s
p
i
r
a
l
s
α
0
.
5
n
u
m
b
e
r
o
f
p
e
r
i
o
d
s
1
2
3
4
5
a
p
p
r
o
x
i
m
a
t
i
o
n
o
r
d
e
r
1
2
3
4
5
6
7
8
9
1
0
s
n
(
α
,
ϕ
)
c
n
(
α
,
ϕ
)
d
n
(
α
,
ϕ
)