Study guide for Examlet 5

$\let\b=\mathbf$ Here is a non-exhaustive list of questions you should be able to answer as you prepare for the examlet.

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(Recall from the course policies that our examlets are cumulative.)

Eigenvectors and Eigenvalues

  • All topics for examlet 4 study guide
  • How do eigenvectors/eigenvalues change under Shift? Inversion? Taking the $n$th power? Taking the inverse?
  • When is a matrix diagonalizable? Are all matrices diagonalizable?
  • How does the error in power iteration behave?
  • Under what circumstances will power iteration converge? When can we not guarantee that it will?
  • What is inverse iteration?
  • What is Rayleigh quotient iteration?
  • How can the power method be applied to find the equilibrium distribution of a Markov chain?

SVD

  • What is the singular value decomposition?
  • What are left/right singular vectors with respect to $A^TA$ and $AA^T$? singular values?
  • What properties do the singular vectors and singular values satisfy?
  • How can the SVD be computed?
  • Given a non-square matrix, what shape do the component matrices of the SVD have? In the 'full' case and the 'reduced' case?
  • How can the SVD be used for low-rank approximation?
  • What is the pseudoinverse? What properties does it satisfy?

Least Squares

  • How can you solve a (square) linear system using the SVD?
  • Why is the SVD helpful for (tall-and-skinny) least-squares system using the SVD? What is the residual in such a problem?
  • How can you solve a least-squares problem using the SVD?
  • Given an SVD of the matrix and a right-hand side, how would you find the 2-norm of the residual of a least-squares problem?
  • How would you use code to solve a (short-and-fat/tall-and-skinny matrix) least-squares problem?

Interpolation

  • What are the drawbacks of equispaced nodes in interpolation? How are those addressed by edge-clustered nodes?
  • What are the drawbacks of monomials as an interpolation basis? How are those addressed by orthogonal polynomials?
  • What does it mean for two functions to be orthogonal?
  • What does it mean for two polynomials to be orthogonal?
  • How are the Legendre polynomials defined? and the Chebyshev polynomials?
  • What are the Chebyshev interpolation nodes?

Numerical Differentiation

  • How can a first/second/third derivative be computed using interpolation? How would that be expressed using Vandermonde matrices?
  • Given point values of a function, how can you use interpolation to compute an approximation of the derivative of that function at the same or different points?
  • What are finite difference formulas?
  • If you shorten the distance between points from, say, $h$ to $h/2$, how will the finite difference formula change?
  • If you shift a finite difference formula from, say $3+h$ to, say, $4+h$, how does the formula change?
  • What is the order of accuracy of this process? (I.e. how does the error depend on $h$?)

Numerical Integration

  • Given point values of a function, how can you use interpolation to compute an approximation of the definite integral (over some interval) of that function?
  • How do quadrature rules make this process more efficient?
  • If you shorten the distance between points from, say, $h$ to $h/2$, how will the quadrature rule change?
  • If you shift a quadrature rule from, say $3+h$ to, say, $4+h$, how does the formula change?
  • What is the order of accuracy of this process? (I.e. how does the error depend on $h$?)