# MATH487, Fall 2018: class plan

#### 8.27

Introduction and course overview

Systems of linear equations.
Gauss elimination

#### 8.29

Basic properties of matrices.
Regular matrices; $$LU$$ decomposition of regular matrices.

#### 8.31

Notion of (matrix) group. Examples: groups of lower, upper triangular matrices. Matrix inverses.
Row swaps and permutation matrices. Group of permutation matrices.
Non-singular matrices and row-echelon normal form.

Determinants: definition.

#### 9.5

Determinant: existence and properties.
Matrix is singular iff its determinant vanishes.
Determinants andÂ $$LU$$ decomposition.
Example: tridiagonal matrices.
Kramer’s rule.

#### 9.7

Remarkable determinants: VanderMonde, Cauchy.
Applications: Lagrange interpolation formula.

#### 9.10

Cauchy-Binet formula and matrix tree theorem.

#### 9.12

General linear spaces.
Linear operators.
Bases. Bases changes.

#### 9.14

Normal forms: mappings between different spaces: normal forms
Endomorphisms: classification problem.
Eigenvectors. Characteristic polynomial.

#### 9.17

Applications: Markov chains; random walks; transition matrices; random walks on binary cubes and on cycles.

#### 9.19

Reminder: complex numbers. Matrix interpretation.

#### 9.21

Jordan normal forms.
Functions of matrices.

#### 9.23

Matrix exponentials.
Shift-invariant spaces of functions, linear ODEs.

#### 9.26

Conjugate spaces.
Mappings to conjugate spaces. Quadratic forms.
Normal forms for quadratic forms. Signature, inertia theorem.

#### 9.28

Statistics; variance, correlations.
Orthogonalization. Orthogonal polynomials.

#### 10.1

Rayleigh min-max theorem; spectra interlacing.

Midterm 1

#### 10.5

Applications: low rank approximations (Netflix problem).

#### Week of 10.8

Rotation matrices in 3D spaces, SO(3).
Roll, pitch, yaw. Commutators; Jacobi identity.

Vector calculus.
Classical identities in 3D; scalar, vector products.

Line integrals.
Integrals over higher-dimensional chains.
Exterior forms.

#### Week of 10.15

Differential forms.
Stokes and relatives.
Applications: data analysis.

#### Week of 10.22

Metric spaces: completeness, examples.
Contractions and their fixpoints.

Hyperbolic spaces.

Complex analysis.
Analytic functions. Cauchy-Riemann.
Laurent series. Domains of convergence.
Integrals via residues.

#### Week of 10. 29

Logarithmic residues, Rouche theorem.
Applications: Ideal fluids.
Fractional-linear mappings.

Midterm 2

#### Week of 11.5

Elements of Fourier transform.
Parseval theorem.
Inverse transform.
Duality (smoothness-localization). “Uncertainty principle”.

#### Week of 11.12.

Elements of asymptotic analysis.
Laplace method. Steepest descent.
Tauber theorems.
Asymptotics for coefficients of generating functions; Darboux transfer.

no classes

#### Week of 11.26

Partial differential equations.
First order equations; examples (eikonal).
Cauchy problem. Quasilinear PDEs.

#### Week of 12. 3

Wave equation: dâ€™Alembert solution.
Wave equation via Fourier series.
Elliptic problems.

#### Week of 12.10

Harmonic functions.
Dirichlet, Neumann.

Course recap.