Let A ∈ Mat n×n(R) be a real square matrix.
(a) Suppose that A is symmetric, positive semi-definite, and
orthogonal. Prove that A is the identity matrix.
(b) Suppose that A satisfies A = −A^T . Prove that if λ ∈ C is
an eigenvalue of A, then λ¯ = −λ.
From now on, we assume that A is idempotent, i.e. A^2 = A.
(c) Prove that if λ is an eigenvalue of A, then λ is equal to 0...
Assingment: for c++
A magic square is an n x n matrix in which each
of the integers 1, 2, 3...n2 appears exactly once and
all column sums, row sums, and diagonal sums are equal. For
example, the attached table shows the values for a 5 x 5 magic
square in which all the rows, columns, and diagonals add up to
65.
The following is a procedure for constructing an n x n magic
square for any odd integer n....
Prove the following theorem:
Theorem
∀n ∈ Z, n is either even or odd (but not both).
Your proof must address the following points:
1. n is even or odd (and nothing else).
2. n is odd =⇒ n is not even (hint: contradiction).
3. n is even=⇒ n is not odd (hint: contrapositive).
The first point is a bit more difficult. Start by making a
statement about 0. Then assuming that n is even, what can you say
about...
Divide and Conquer (Strassen’s Matrix
Multiplication)
Given two square matrices A and B of size n x n each, find their
multiplication matrix.
Naive Method
Following is a simple way to multiply two matrices.
void multiply(int A[][N],
int B[][N], int C[][N]) {
for
(int i = 0; i < N; i++) {
for
(int j = 0; j < N; j++) {
C[i][j]
= 0;
for
(int k = 0; k < N; k++) {
C[i][j]
+= A[i][k]*B[k][j];
}...
Suppose C is a m × n matrix and A is a n × m matrix. Assume CA =
Im (Im is the m × m identity matrix). Consider the n × m system Ax
= b.
1. Show that if this system is consistent then the solution is
unique.
2. If C = [0 ?5 1
3 0 ?1]
and A = [2 ?3
1 ?2
6 10] ,,
find x (if it exists) when
(a) b =[1...
Linear Algebra
Carefully prove the following statement:
Let A be an n×n matrix. Assume that there exists an integer k ≥
1 such that Ak = I . Prove that A is invertible.
Use this theorem to find the inverse of the given matrix or show
that no inverse exists. (If an answer does not exist, enter DNE in
any cell.)
1
2
5
1
−1
0
2
1
2
1
−5
0
1
1
2
1