1.4 Review of lectures

Table 1.1: Class lectures review




#

date

book section

note





1

Sept 3, 2019

Chapter 1

Order of ODE, On Laplacian, why it shows up so frequently everywhere, review





2

Sept 5, 2019

Chapter 2

Transport PDE \(u_t+c u_x=0\), characteristic lines. Transport with decay \(u_t+c u_x+ au=0\)





3

Sept 10, 2019

Chapter 2

Continue with Transport PDE \(u_t+c u_x=0\), examples \(u_t+(x^2-1)u_x=0, u(0,x)=e^{-x^2}\)





4

Sept 12, 2019

Chapter 2.4

Wave equation \(u_{tt}=c^2 u_{xx}\), derivation of d’Alembert solution on infinite line. Example. Domain of influence. Also with external force. Resonance





5

Sept 17, 2019

Chapter 3

Starting Fourier series. Heat PDE \(u_t= k u_{xx}\). Separation of variables. Periodic boundary conditions (ring). Obtain Fourier series solution. How to find coefficients, convergence, etc...





6

Sept 19, 2019

Chapter 3

More Fourier series. \(f(x) \in L_2\), definition of norm of \(f(x)\), basis functions. How to find Fourier coefficients. Example using \(f(x)=x\). Definitions, jump discontinuity. Fourier series convergence theorem.





7

Sept 24, 2019

Chapter 3

even and odd functions. Complex Fourier series. Example.





8

Sept 26, 2019

Chapter 3

Integration of Fourier series. Find F.S. of \(f(x)\) using integration of known F.S. for \(g(x)\). Convergence of functions Uniform and piecewise. M test.





9

Oct 1, 2019

Chapter 3

More on convergence. Convergence in norm. Definitions and examples. More theories on Fourier series convergence. Bessel inequality. Proof (long). Riemann-Lebesgue Lemma





10

Oct 3, 2019

Chapter 3

Decay and smoothness of Fourier series. Proof of the Fourier series convergence theorem. Dirichlet kernel.





11

Oct 8, 2019

N/A

First exam





12

Oct 10, 2019

Chapter 4

Heat ODE \(u_t=k u_{xx}\), going over instantaneous smoothness. Transport PDE we can go back and forward in time, but not with heat PDE. Heat PDE with non zero boundary conditions





13

Oct 15, 2019

Chapter 4

Root cellar problem. Solving heat PDE in complex domain example. Starting on wave equation. Fourier series solution





14

Oct 17, 2019

Chapter 4

Solving wave PDE on finite domain using d’Alembert. 2 cases. B.C. B.C. is Neumann and B.C. is Dirichlet (Even and Odd extension of initial position). Solving Laplace PDE \(u_{xx}+u_{yy}=0\) on rectangle.





15

Oct 22, 2019

Chapter 4.3

Laplace in disk. Polar coordinates. Separation of variables. Converting back the solution from polar to Cartesian coordinates. Closed form integral formula.





16

Oct 24, 2019

Chapter 4.4

Closed form integral solution for Laplace PDE inside disk. thm 4.6 and thm 4.9 (max or min of solution at boundary), thm 4.11. Classification of PDE’s. General formula to find characteristic curves.





17

Oct 29, 2019

Chapter 6

Delta function. Definitions. Two cases, using limits and using integral. Integration of delta function, differentiation. Introduction to Green function





18

Oct 31, 2019

Chapter 6.2

Green function. Examples for \(-u''(x)=f(x)\) with Dirichlet and Neumann B.C. Full derivation





19

Nov 5, 2019

Chapter 6.2

More Green function. Neumann B.C. Higher dimensions Green function. Laplace on square. Exam review





20

Nov 7, 2019

Second exam





21

Tuesday Nov 12, 2019

Chapter 6

Green function in higher dimensions. On whole plane. Green formula. Review of multivariable calculus. Derivation of Green function in 2D and 3D on whole space. Exam 2 returned.





22

Thursday Nov 14, 2019

Chapter 6

Green function. Method of images. half space and disk. Eigenfunctions





23

Tuesday Nov 19, 2019

Chapter 6

Eigenfunctions and eigenvalues for Laplacian in 2 and 3D. Behaviour of eigenvalues, Weyl law for eigenvalues. Solving PDE on 2D.





24

Thursday Nov 21, 2019

Chapter 6

Laplacian is energy minimizer. Equivelance between \(E(u)=\int{ 1/2 | \triangle (u) |^2 -f u \, dx}\) and solution to \(-\triangle (u)=f\) with Dirichlet B.C. Proofing that if \(u\) solves Laplace PDE then it minimizes the energy. And proofing that if \(u\) minimizes energy then it solves Laplace PDE





25

Tuesday Nov 26, 2019

Chapter 6

Fourier transform. Derivations and two examples using a box function and Gaussian \(e^{-x^2}\)