关键词 > COMP3670/6670
COMP3670/6670: Introduction to Machine Learning Semester 2, 2022 Assignment 4
发布时间:2022-10-19
Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit
Semester 2, 2022
Assignment 4 Theory Questions
COMP3670/6670: Introduction to Machine Learning
Question 1 Permutation Matrix (5+5=10 credits) A permutation matrix is a square matrix that has exactly a single 1 in every row and column, and
zeros elsewhere. For example,
'0 |
1 0 0 0 |
0 0 0 1 |
0(0)┐'
|
Let P be an arbitrary | ↓ | permutation matrix.
1. Prove that P is always invertible.
2. Prove that PT is a permutation matrix.
Question 2 Distinct eigenvalues and linear independence (20+5 credits)
Let A be a | ↓ | matrix.
1. Suppose that A has | distinct eigenvalues λ 1 |...| λn, and corresponding non-zero eigenvectors x1 |...| xn . Prove that #x1 |...| xn} is linearly independant.
Hint: You may use without proof the following property: If #y1 |...| ym} is linearly dependent then there exists some p such that 1 女 p 长 m, yp+1 ∈ span#y1 |...| yp} and #y1 |...| yp} is linearly independent.
2. Hence, or otherwise, prove that for any matrix B ∈ Rn xn , there can be at most | distinct eigenvalues for B.
Question 3 Properties of Upper Triangular (10+15=25 credits)
1. Prove the set of all lower triangular matrices is closed under matrix multiplication.
2. Let U be an square | ↓ | lower triangular matrix. Prove that the determinant of U is equal to the product of the diagonal elements of U.
Question 4 Eigenvalues of symmetric matrices (15 credits)
1. Let A be a symmetric matrix. Let v1 be an eigenvector of A with eigenvalue λ 1 , and let v2 be an eigenvector of A with eigenvalue λ2 . Assume that λ 1 λ2 . Prove that v1 and v2 are orthogonal. (Hint: Try proving λ 1v1(T)v2 = λ2v1(T)v2 . Recall the identity aT b = bT a.)
Question 5 Computations with Eigenvalues (3+3+3+3+3=15 credits)
Let A = ┌3(6) 5(4)┐ .
1. Compute the eigenvalues of A.
2. Find the eigenspace #入 for each eigenvalue λ . Write your answer as the span of a collection of vectors.
3. Verify the set of all eigenvectors of A spans R2 .
4. Hence, find an invertable matrix P and a diagonal matrix D such that A = PDP-1 .
5. Hence, find a formula for efficiently 1 calculating An for any integer | ≥ 0. Make your formula as simple as possible.