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20 votes
3 answers
3k views

Why is there not a test for diagonalizability of a matrix

Let $A$ be square.This question is a bit opinion based, unless there is a technical answer.I think it is helpful tho. Also this question is closely related to this question : quick way to check if a ...
Mahammad Yusifov's user avatar
1 vote
0 answers
49 views

Estimating the parameters of an ellipse

Problem definition Consider a dataset composed by $m$ bivariate measurements \begin{equation*} y_j \sim \mathcal{U}(\mathcal{E}(\ell_1,\ell_2,\theta)) \qquad j=1,2,\dots,m \end{equation*} uniformly ...
matteogost's user avatar
2 votes
1 answer
190 views

How to block diagonalize a orthogonal matrix?

I am trying to block diagonalize a real orthogonal matrix, A. The condition is that the blocks should also be orthogonal. I found this pretty old yet abstract paper that says "By block ...
Pro's user avatar
  • 71
0 votes
0 answers
20 views

Discussion about diagonalizing matrix

I have equation $I = \rho(r)^{T} A_{h} \rho(r)$, where $\rho(r)= \begin{pmatrix}\rho_{+}(r) \\ \rho_{-}(r) \\ \rho_{z}(r)\end{pmatrix}$. I want to rearrange $I$ by diagonalizing $A_{h}$ such as $\...
Yeongkyu Lee's user avatar
0 votes
1 answer
83 views

SVD of product of diagonal and unitary matrices

Given two (possibly rectangular) diagonal matrices $\Sigma_\text{L}$ and $\Sigma_\text{R}$ with nonnegative elements, what can we say about the singular value decomposition of $$\Sigma_\text{L} X \...
SnowzTail's user avatar
0 votes
1 answer
77 views

Simultaneous diagonalization of a positive semi-definite matrix and a symmetric matrix

Let $A,B$ be $d\times d$ symmetric matrices with real coefficients such that $A$ is positive semi-definite. Prove that $\det(tA+B)\in \mathbb{R}[t]$ is either $0$ or has all roots real. Here is what ...
Takamoto Yuji's user avatar
1 vote
1 answer
67 views

Faulty algorithm for simultaneous diagonalization?

I found a simple algorithm for simultaneous diagonalization of two commuting matrices (https://doi.org/10.48550/arXiv.2006.16364), which seemed to be well-founded. For commuting matrices $\mathbf{A}$ ...
TobiR's user avatar
  • 528
1 vote
1 answer
691 views

Can we use the singular value decomposition to compute the matrix exponential for a non-diagonalisable matrix?

For a diagonalisable matrix $ \bf{A} $ with eigendecomposition $ \bf{A} = \bf{U} \bf{\Lambda} \bf{U}^{-1} $, we know that $ \exp(\bf{A}) = \bf{U} (\exp \bf{\Lambda}) \bf{U}^{-1} $, where $ \exp \bf{\...
Nick_2440's user avatar
  • 332
2 votes
1 answer
92 views

How to diagonalize this (close-to-diagonal) matrix fast?

I have a symmetric matrix that looks like this. (Note that they are not the normal tridiagonal matrices, the diagonals are one diagonal apart). It would be a fairly large matrix. What would be some ...
orangecat's user avatar
  • 303
8 votes
3 answers
272 views

Find the $n$th power of a 3-by-3 circulant matrix

Consider the matrix given as $$A=\begin{bmatrix}a_0 & a_2 & a_1\\ a_1 & a_0 & a_2\\ a_2 & a_1 & a_0\end{bmatrix}$$ Write a formula for $A^n$ for $n\in\mathbb{N}$. $$$$ My ...
mrx king's user avatar
  • 161
0 votes
1 answer
41 views

Relationship between rows and columns of an orthogonal matrix in a spectral decomposition

I am trying to derive the relation $\mathbf A=\mathbf V^T\boldsymbol\Lambda\mathbf V=\sum_{i=1}^n\lambda_i\mathbf v_i\mathbf v_i^T$, where $\mathbf A$ is symmetric, $\mathbf V$ orthogonal (where $\...
A5kar's user avatar
  • 21
0 votes
1 answer
79 views

Can a certain matrix $A$ be diagonalized by a rotation matrix? [closed]

I have matrix $$\mathcal{A}=\pmatrix{a & c \\ c & b}$$ I can diagonalize this matrix by $\mathcal{A} = SDS^{-1} \Rightarrow D=S^{-1}\mathcal{A}S$, where $D$ is diagonalized matrix consists of ...
Yeongkyu Lee's user avatar
2 votes
0 answers
93 views

Conditions under which a non-symmetric block matrix is diagonalisable

I have a $(2n)\times (2n)$ matrix defined in blocks: $$ \begin{equation} \begin{split} M=\left[ \begin{array}{c|c} A & B\\ \hline C & D \\ \end{array} \right] \end{split} \end{equation} $$ ...
Chaos's user avatar
  • 299
0 votes
1 answer
63 views

One matrix is diagnolized by orthonormal basis of another matrix

Let $A\in \mathbb R^{n\times n}$. Suppose $B$ is symmetric and positive definite, and \begin{equation}\label{eq:sym} A^TB=BA, \end{equation} then $A$ is diagnolizable by a B-orthonormal basis. ...
Rakuten's user avatar
0 votes
1 answer
47 views

Question about inverse of a matrix.

Consider the block upper triangular matrix $$A = \left[ \begin{matrix} A_{11} & A_{12} \\ 0 & A_{22} \end{matrix} \right], $$ where $A\in\mathbb R^{n\times n}$ and $A_{11}\in\mathbb R^{k\times ...
Owen Murphy's user avatar

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