Questions tagged [circulant-matrices]
For questions regarding circulant matrices, where each row vector is rotated one element to the right relative to the preceding row vector.
150 questions
1 vote
0 answers
69 views
Eigenvalues of real left-circulant matrices
Consider the $3\times3$ left-circulant matrix with first row $(0,1,1)$: $$ C = \begin{pmatrix} 0 & 1 & 1 \\ 1 & 1 & 0 \\ 1 & 0 & 1 \end{pmatrix} $$ where each row is a left ...
1 vote
0 answers
61 views
Can the unitary transformation of one of the matrix preserve the invertibility of Hadamard product? [closed]
Let $A=[a_{ij}],B=[b_{ij}]\in \mathcal{M}_{n}(\mathbb{R})$ be two invertible matrices and additionally, their Hadamard product $A\odot B$ is also invertible. Consider the basic circulant permutation ...
3 votes
2 answers
90 views
Solve linear system with non-invertible circulant matrix
I would like to solve a linear system $Ax = b$, where $A$ is given by the circulant matrix $$ A = \begin{bmatrix} 1 & 0 & 0 & \ldots & 0 & 0 & -1\\ -1 & 1 & 0 & \...
1 vote
1 answer
136 views
Eigenstructure of (Symmetric Block-Circulant) Covariance Matrix from Modular Arithmetic
I'm trying to understand the eigenvalues of a particular block-circulant matrix $\Sigma$. I'm studying modular arithmetic, specifically $x + y \pmod p$. I call $p$ the "modulus" or the "...
3 votes
2 answers
354 views
Is Johnson Graph J(N, 2) circulant?
I have stumbled upon the problem of diagonalizing the matrix of a Johnson graph $(N,k)$ with $k=2$. From Wikipedia and several other references I found the explicit form for the eigenvalues https://en....
3 votes
1 answer
226 views
How to compute the determinant of a block circulant matrix?
I am curious if there are any general formulas for problems like this or special cases. I want to compute the determinant of $2n \times 2n$ complex matrices made of identical $2 \times 2$ matrices. If ...
1 vote
2 answers
168 views
Determinant of the circulant matrix corresponding to the $r$-tuple $(1, 1, 0, 0, \ldots , 0, 0)$
For any integer $r \geq 3$, consider the $r$-tuple $(1, 1, 0, 0, \ldots , 0, 0)$ (involving $r - 2$ zeros) which represents the first row of the corresponding $r \times r$ circulant matrix. Show that ...
1 vote
1 answer
105 views
Spectrum of circulant block matrix of circulant blocks (Adjacency matrix of discrete torus)
I am currently investigating the spectrum of a matrix $M \in \mathbb{R}^{12 \times 12}$. The matrix has the following form, $$ M = \begin{bmatrix} 0 & 1 & 0 & 1 & 1 & 0 &...
3 votes
2 answers
235 views
The inverse of the "Given vertices find area of polygon in complex plane" problem
Let $\omega_0, \ldots, \omega_{n-1}$ be the $n$-th roots of unity, and $a_0, \ldots, a_{n-1}$ be real numbers in the $(0, 1]$ interval. Define $z_i = a_i \omega_i$ as the vertices of a polygon on the ...
0 votes
0 answers
60 views
Relation for maximum eigenvalue of 2-tridiagonal Toeplitz matrix
Let an 8x8 2-tridiagonal Toeplitz matrix is of the form S1. From the literature Eigenvalues of 2-tridiagonal Toeplitz matrix its easy to findout the maximum eigenvalue of S1. S1=$ \begin{bmatrix} a &...
1 vote
0 answers
54 views
What is the correct terminology for this circulant & symmetric matrix with only two distinct elements?
Is there a special terminology to describe a matrix of the following form in $\mathbb{C}^{4\times 4}$ or more generally $\mathbb{C}^{N\times N}$? $\begin{bmatrix} a & b & b & b \\ b & ...
2 votes
1 answer
101 views
Are there real normal matrices with non-negative entries that are asymmetric and non-circulant?
Is there an example of a normal matrix with real non-negative entries that is neither symmetric nor circulant/block-circulant? If not, is there a proof of this property/reference to proof? ...
5 votes
1 answer
182 views
Coefficients of a symmetric product of polynomials with root of unity
For number $n\ge2$, let $\xi$ be a primitive $n$-th root of unity. The determinant of circulant matrix is a symmetric polynomial in $x_0,\dots,x_{n-1}$ $$f_n=\prod_{j=0}^{n-1}\sum_{i=0}^{n-1}ξ^{ij}x_i$...
0 votes
0 answers
119 views
Conditions for solving a Circulant-plus-diagonal system
Let $\matrix{C}$ be a $n \times n $ circulant matrix with generating vector $\vec{c} = \{0 , c_1, c_2, \cdots, c_k, 0,\cdots, 0\} $ where $k \le n-1$. Let $\matrix{A}$ be a diagonal matrix with ...
0 votes
1 answer
121 views
Prove that for every root of unity $z$ of size $n$, the vector ($1, z, z^2,..., z^{n-1}$) is an eigenvector of the circulant matrix $A$ [closed]
Let $a_1, a_2, \dots, a_n \in \Bbb{C}$. Let $$ A = \begin{bmatrix} a_1 & a_2 & \dots & a_{n-1} &a_n\\ a_n & a_1 & \dots & a_{n-2} & a_{n-1}\\ \vdots & \vdots & \...