MATH 240
The exam will cover the material we have discussed in class and studied in homework, from Sections 5.1-5.6 and Sections 6.1 to 6.6.
The following list points out the most important definitions and theorems.
Note that when a computation is required, you may be asked to justify the conclusion you draw from the computation (by mentioning a fact or theorem, for example)
Definitions:
- Eigenvalue, eigenvector, eigenspace
- Characteristic polynomial, characteristic equation
- Similar matrices, diagonalizable matrix
- Matrix of a linear transformation
- Inner product, length (or norm) of a vector, orthogonality
- Orthogonal complement
- Orthogonal sets, orthonormal sets
- Orthogonal basis, orthonormal basis
- Orthogonal projections
- Gram-Schmidt process
- The QR factorization will not be on the test
- Least squares problem, normal equations
Theorems:
Chapter 5:
- Theorem 2 (Linear independence of eigenvectors corresponding to distinct eigenvalues)
- Theorem 4 (Similar matrices have the same characteristic polynomial)
- Theorems 5 & 6 (Diagonalization)
- Theorem 8 (Diagonal matrix representation)
- Theorem 9 ('Hidden rotations')
Chapter 6:
- Theorem 2 (Pythagorean theorem)
- Theorem 4 (Linear independence of nonzero orthogonal vector)
- Theorems 5 (Orthogonal decomposition)
- Theorems 6,7 (Orthogonal matrices)
- Theorems 8,9,10 (Orthogonal projections)
- Theorem 11 (Gram-Schmidt)
- Theorem 13 (Normal equations)
Important Skills (partial list):
- Decide whether a vector is an eigenvector of a matrix.
- Find the eigenvalues of a triangular matrix
- Find the eigenvectors corresponding to a known eigenvalue. Find a basis for an eigenspace.
- Find the eigenvalues and eigenvectors of a 2× 2 matrix A.
- Diagonalize a matrix given its eigenvalues.
- Find the matrix of a linear transformation (e.g p.333:1,p.334:11).
- Find the complex eigenvalues and corresponding eigenvectors of a 2× 2 matrix A.
- Find a factorization of a 2x2 matrix with a complex eigenvalue (e.g. p. 341:13)
- Find the solution of a difference equation xk+1= A xk using the eigenvectors and eigenvalues of A. Be able to classify the origin as an attractor, a repellor or a saddle point.
- Compute the length of a vector. Normalize a vector.
- Check a set for orthogonality.
- Find the coordinates of a vector relative to an orthogonal basis.
- Compute the orthogonal projection of one vector onto another.
- Compute the orthogonal projection of a vector onto a subspace. Find the distance from a vector to a subsapce. Decompose a vector as in the Orthogonal Decomposition Theorem.
- Apply the Gram-Schmidt process to a set of vectors.
- Solve a least squares problem by using the normal equations.
Further Review:
Some sample exam questions can be found at
www.laylinalgebra.com. The
following problems are relevant:
Course A, Third Exam: Questions 3, 4, 5, 6, 7 and 8.
Course B, Second Exam: Questions 4 and 7.
Course B, Third Exam: Questions 2, 3 and 7 and 8
Course C, Third Exam: Questions 1, 2, 3 and 4
All of the exams on the Web/CD are from exams given at the University of Maryland.