SOLUTIONS MANUAL
,Selected Solutions Manual
for Instructors
for
Introduction to Partial
Differential Equations
by
Peter J. Olver
Undergraduate Texts in Mathematics
Springer, 2014
ISBN 978–3–319–02098–3
c 2020 Peter J. Olver
,Table of Contents
Chapter 1. What Are Partial Differential Equations? . . . . . . . . . . 1
Chapter 2. Linear and Nonlinear Waves . . . . . . . . . . . . . . . . 3
Chapter 3. Fourier Series . . . . . . . . . . . . . . . . . . . . . 14
Chapter 4. Separation of Variables . . . . . . . . . . . . . . . . . 29
Chapter 5. Finite Differences . . . . . . . . . . . . . . . . . . . 43
Chapter 6. Generalized Functions and Green’s Functions . . . . . . . 60
Chapter 7. Fourier Transforms . . . . . . . . . . . . . . . . . . . 71
Chapter 8. Linear and Nonlinear Evolution Equations . . . . . . . . 77
Chapter 9. A General Framework for
Linear Partial Differential Equations . . . . . . 87
Chapter 10. Finite Elements and Weak Solutions . . . . . . . . . . . 99
Chapter 11. Dynamics of Planar Media . . . . . . . . . . . . . . . 110
Chapter 12. Partial Differential Equations in Space . . . . . . . . . . 126
c 2020 Peter J. Olver
, Selected Solutions to
Chapter 1: What Are Partial Differential Equations?
Note: Solutions marked with a ⋆ do not appear in the Student Solutions Manual.
1.1. (a) Ordinary differential equation, equilibrium, order = 1;
(c) partial differential equation, dynamic, order = 2;
(e) partial differential equation, equilibrium, order = 2;
⋆ (g) partial differential equation, equilibrium, order = 2;
⋆ (i) partial differential equation, dynamic, order = 3;
⋆ (k) partial differential equation, dynamic, order = 4.
∂2u ∂2u
1.2. (a) (i) + = 0, (ii) uxx + uyy = 0;
∂x2 ∂y2
∂u ∂2u ∂2u
⋆ (c) (i)
∂t
=
∂x2
+
∂y2
, (ii) ut = uxx + uyy .
1.4. (a) independent variables: x, y; dependent variables: u, v; order = 1;
⋆ (b) independent variables: x, y; dependent variables: u, v; order = 2;
⋆ (d) independent variables: t, x, y; dependent variables: u, v, p; order = 1.
∂2u ∂2u
1.5. (a) + = ex cos y − ex cos y = 0; defined and C∞ on all of R 2 .
∂x2 ∂y2
∂2u ∂2u
⋆ (c) + = 6 x − 6 x = 0; defined and C∞ on all of R 2 .
∂x2 ∂y2
∂2u ∂2u 2 y2 − 2 x2 2 x2 − 2 y2
⋆ (d) + = + = 0; defined and C∞ on R 2 \ {0}.
∂x2 ∂y2 (x2 + y2 )2 (x2 + y2 )2
h i
1.7. u = log c (x − a)2 + c (y − b)2 , for a, b, c arbitrary constants.
⋆ 1.8. (a) c0 + c1 x + c2 y + c3 z + c4 (x2 − y2 ) + c5 (x2 − z 2 ) + c6 x y + c7 x z + c8 y z,
where c0 , . . . , c8 are arbitrary constants.
∂2u ∂2u ∂2u ∂2u
1.10. (a)
∂t2
− 4
∂x2
= 8 − 8 = 0; ⋆ (c) ∂t2
− 4
∂x2
= −4 sin 2 t cos x + 4 sin 2 t cos x = 0.
1.11. (a) c0 + c1 t + c2 x + c3 (t2 + x2 ) + c4 t x, where c0 , . . . , c4 are arbitrary constants.
b b
⋆ 1.13. u = a +
r
=a+ q , where a, b are arbitrary constants.
x2 + y2 + z 2
c 2020 Peter J. Olver