`
u
[
x
_
,
y
_
,
m
_
]
:
=
m
∑
n
=
1
2
S
i
n
h
[
n
*
π
]
*
1
2
(
n
*
π
)
*
S
i
n
(
n
*
π
)
2
+
1
n
*
π
*
S
i
n
(
n
*
π
)
2
*
S
i
n
[
n
*
π
*
x
]
*
S
i
n
h
[
(
1
-
y
)
*
n
*
π
]
P
l
o
t
3
D
[
u
[
x
,
y
,
m
]
,
{
x
,
0
,
1
}
,
{
y
,
0
,
1
}
,
{
5
0
}
]