ECE-GY 5253 Midterm Applied Matrix Theory Spring 2023
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Applied Matrix Theory
ECE-GY 5253 Midterm
Spring 2023
Due: Tuesday, March 21, 8 pm (Eastern Time)
Problem 1
For a given matrix A = 1(1) 1 2, is matrix A diagonalizable? If yes, diagonalize the matrix;
otherwise, give the Jordan form. Show detailed steps to solve the problem.
Problem 2
If true, write proof; If false, give a counter-example.
(a) If A ∈ Rn ×m and AAT is invertible, then rank(A) = n.
(b) For matrices A,B ∈ Rn ×n , if AB = BA = 0, then A = 0 or B = 0.
(c) If B ∈ Rn ×n is symmetric with strictly positive eigenvalues (i.e., λi > 0 for i = 1, . . . ,n) then B is invertible.
(d) For any A ∈ Rm ×n and any α > 0, AT A + αI is always invertible.
(e) For all A ∈ Rn ×n , if v1 ∈ Rn ia an eigenvector of A associated with the eigenvalue λ 1 and if v2 ∈ Rn is an eigenvector of A associated with eigenvalue λ2 λ 1 , then v1 + v2 is an eigenvector of A associated with the eigenvalue λ 1 + λ2 .
Problem 3
(a) Let M ∈ Rn ×n be a symmetric matrix whose eigenvalues are strictly positive. Show that for all u,v ∈ Rn
(uT Mv) 2 ≤ (uT Mu) (vT Mv) .
(b) Let M ∈ Rn ×n be a symmetric matrix such that M2020 = In (In ∈ Rn ×n : identity matrix). Compute M2 (Justify your answer).
2023-04-27