CS223 · Chapter 5 · Annotated SlidesComplex Eigenvalues and Dynamical Systems
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Complex Eigenvalues and Dynamical Systems

Complex eigenvalues and eigenvectors in conjugate pairs, rotation–scaling matrices, long-term behaviour of xₖ₊₁ = Axₖ, population models and steady-state vectors.

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Every original slide is shown unchanged. Yellow marks on a slide point to a numbered note: hover or tap a mark to jump to its note, and hover a note to see its marks. Questions tagged Past exam appeared on a real paper; Prediction questions are likely angles, not confirmed. Pick an answer to each question: a wrong pick tells you why it is wrong, so you can try again.

All 18 slides
  1. 1 Slide 1
  2. 2 Slide 2
  3. 3 Slide 3
  4. 4 Long-term evaluation: Example
  5. 5 eigenfunctions of the differential equation
  6. 6 Example:
  7. 7 Slide 7
  8. 8 Slide 8
  9. 9 Slide 9
  10. 10 Slide 10
  11. 11 Slide 11
  12. 12 Slide 12
  13. 13 Example:
  14. 14 Slide 14
  15. 15 Slide 15
  16. 16 Slide 16
  17. 17 k
  18. 18 Example:
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Notes

  1. For real A, complex eigenvalues come in conjugate pairs λ, λ̄ with eigenvectors x, x̄.

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Long-term evaluation: Example

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Notes

  1. Long-term behaviour of xₖ = Aᵏx₀: write x₀ in the eigenvector basis; terms with |λ| > 1 grow, |λ| < 1 decay.

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eigenfunctions of the differential equation

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Example:

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Example:

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Notes

  1. Steady-state vector of a stochastic (Markov) matrix P: Pq = q with entries summing to 1: solve (P − I)q = 0.

Exam angle

PredictionQ1

How do you find the steady-state vector of a stochastic matrix P?

Compare with the model answer

Solve (P − I)x = 0, pick a nonzero solution, and scale it so its entries add up to 1.

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k

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Example:

Slide 18: Example: