Ordinary Differential Equations I Math 645
Fall 2011


Instructor Brian Hassard

Lectures M W F 11:00-11:50 Math 150

First-week handout Syllabus, grading policy, important dates

Homework See class

Materials
  interchange of limits p. 17
  generalized eigenvector (wiki)
  Jordan Normal Form
  E invariant with respect to flow p58
  test1_examples_645_20111020.pdf
 
Test1 question 2 β(x0,y0) for y0 neg.
Test1 question 2 show improper integral finite
 
section_2.10_examples.html, section_2.10_examples.pdf,
examples 1-6, also exer. 5c,5d section 2.9
Maple code/graphs
 
645_section_2.11_examples.html, 645_section_2.11_examples.pdf
2d systems:
hyperbolic and elliptic sectors,
saddle-node (two hyperbolic sectors and on parabolic sector)
cusp,
two elliptic and two parabolic sectors,
also center manifold in 2d system example 1, section 2.12
 
645_section_2.12_center_manifold_examples.html, 645_section_2.12_center_manifold_examples.pdf,
3d plots of trajectories and of approximate center manifold;
2d plots of trajectories restricted to appx. center manifold.
section_2.4_p85_exer3_finite_arclength.pdf

Background material for section 2.3 exercise 4.
Heine_Cantor_for_real_nxn_matrix-valued_function.pdf
Includes proof for a real-valued function, and proof of a matrix norm inequality.
These results are then used to show that
a general real nxn matrix-valued function A(t,y),
continuous for (t,y) in K = {-a1≤t≤a1,|y-y0|≤b}
is also uniformly continuous. Here "continuous" and "uniformly continuous" are defined using the matrix norm ||.||.
See also matrix norm inequalities, Heine-Cantor
  645_section_3.2_exercise4.html
Maple workspace with animations showing
trajectories Γ such that ω(Γ) consists of
  • one limit orbit
  • one limit orbit and one equilibrium point,
  • two limit orbits and two equilibria.
In the following, each trajectory "slows down" as it passes closer and closer to (0,0) and (1,0) which are equilibria. The top half y>0 and the bottom half y<0 of the circle (x-1/2)2+y2 are each limit orbits for each of the three trajectories.
645_section_3.2_exercise4A.html
Maple workspace with animations showing
trajectories Γ such that ω(Γ) consists of
  • one limit orbit and one equilibrium,
  • two limit orbits and one equilibrium,
  • three limit orbits and two equilibria
In the following, trajectories "slow down" as they pass closer and closer to (1/2,0) and ((1/2)(1-sqrt(2)),0) which are equilibria.
The outer orbit Γ is such that &omega(Γ) consists of the two equilibria and three limit orbits.
The inner left orbit Γ is such that &omega(Γ) consists of the two equilibria and two limit orbits, the top and bottom halves of the left "eye" outline.
The inner right orbit &Gamma is such that &omega(Γ) consists of the equilibrium (1/2,0) and a limit orbit, the right "eye" outline.


Brian Hassard, Dec. 8, 2011