438 CHAPTER 11 • APPLICATIONS OF HARMONIC FUNCTIONS
- Find the function <fi (x, y) that is harmonic in the upper half-plane Im (z) > 0 and
has the boundary values
- Find the function
(x,y) that is harmonic in the upper half-plane Im(z) > 0 and
has t he boundary values
<fi(x, 0) = 3,
<f>(x, 0) = 1,
for x < -3, and <fi(x, 0) = 7, for - 3 < x < - 1;
for -l<x<2, and (x,0)=4, forx>2.
- F ind t he function <fi (x, y) that is harmonic in the first quadrant x > O, y > 0 and
has the boundary values
<f>(O, y) = 0 ,
</>(x, O} = 1,
for y > 1,
for 0 ~ x < l,
and <fi (0, y) = 1, for 0 < y < l ;
and <fi (x, 0) = 0, for x > 1.
- Find the function
(x, y) that is harmonic in the unit disk lz l < 1 and has t he
boundary values
<fi(x, y) = 0,
<f>(x, y) = 5,
for x + i y = z = eiD, O < 8 < 11';
for x+iy = z = ei^8 , 11' < 8 < 211'.
- Find the function
(x, y) that is harmonic in the unit disk lzl < 1 and has t he
boundary values
<fi(x, y) = 4,
for x + i y = z = ei^9 , 0 < 8 < 11';
forx+iy= z = ei^9 , 11'<8<211'.
- Find the function
(x, y) that is harmonic in the upper half-disk y > 0 , lzl < 1
and has the boundary values
<f>(x, y) = 5,
<f>(x, 0) = -5,
for x + iy = z = e;^8 , 0 < 8 < 11';
for-l<x<l.
10. F ind the function </> (x, y) that is harmonic in the portion of the upper half-plane
Im (z} > 0 that lies outside the circle lzl = 1 and has the boundary values
<f>(x, y) = l ,
<f>(x, 0) = 0 ,
for x + iy = z = e'^9 , 0 < 8 < 11';
for lxl > 1.
Hint: Use the mapping w = -,^1 and the result of Example 11.9.