Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 91764

The study of the properties of real and complex matrices that are more close to analysis and operator theory. For instance: the properties of positive definite matrices, matrix inequalities, perturbation analysis, matrix functions, inequalities between eigenvectors and singular values, majorization.

1 vote

Minimizing $\|X-X_0\|_F^2+\|X^{-1}-Y_0\|^2_F$ with respect to matrix $X$

Given $\mathrm X_0, \mathrm Y_0 \in \mathbb R^{n \times n}$, $$\begin{array}{ll} \text{minimize} & \|\mathrm X - \mathrm X_0\|_F^2 + \|\mathrm Y - \mathrm Y_0\|_F^2\\ \text{subject to} & \mathrm Y = …
Rodrigo de Azevedo's user avatar
1 vote

Minimizing $\|X-X_0\|_F^2+\|X^{-1}-Y_0\|^2_F$ with respect to matrix $X$

Given $\mathrm X_0, \mathrm Y_0 \in \mathbb R^{n \times n}$, $$\begin{array}{ll} \text{minimize} & \|\mathrm X - \mathrm X_0\|_F^2 + \|\mathrm Y - \mathrm Y_0\|_F^2\\ \text{subject to} & \mathrm Y \m …
Rodrigo de Azevedo's user avatar
4 votes

Solving $\text{trace}\left[\left(I + pY\right)^{-1} \left(I - p^{2}Y\right)\right] = 0$ for ...

Given $\mathrm A \in \mathbb R^{n \times n}$, we define $f : \mathbb R \to \mathbb R$ as follows $$f (x) := \mbox{tr} \left( (\mathrm I_n + x \mathrm A)^{-1} (\mathrm I_n - x^2 \mathrm A) \right)$$ …
Rodrigo de Azevedo's user avatar
9 votes

Is there a name for matrices of the form $a_{ij}=\frac{1}{a_{ji}}$?

Some call them currency exchange matrices. From Boyd & Vandenberghe's Introduction to Applied Linear Algebra: 6.7 Currency exchange matrix. We consider a set of $n$ currencies, labeled $1,\dots,n$. ( …
Rodrigo de Azevedo's user avatar
1 vote

Behavior of matrix rank under thresholding of its elements

In some cases, the rank is preserved under thresholding. For example, let $$\rm A := \begin{bmatrix} 1\\ 0\\-1\end{bmatrix} \begin{bmatrix} 1\\ 1\\ 1\end{bmatrix}^\top = \begin{bmatrix} 1 & 1 & 1\\ 0 …
Rodrigo de Azevedo's user avatar
5 votes

Is this inequality involving the Frobenius norm right?

Given $\mathrm A \in \mathbb R^{m \times n}$ and $\mathrm B \in \mathbb R^{n \times p}$, let $\mathrm B \mathrm B^{\top} = \mathrm Q \Lambda \mathrm Q^{\top}$ be an eigendecomposition of $\mathrm B \m …
Rodrigo de Azevedo's user avatar
3 votes

Determinant of a $k \times k$ block matrix

Let us assume that $A-B$ is invertible. Write $$\begin{array}{rl} C &= \begin{bmatrix} A & B & \ldots & B\\ B & A & \ldots & B\\ \vdots & \vdots & \ddots & \vdots\\B & B & \ldots & A\end{bmatrix}\\\\ …
Rodrigo de Azevedo's user avatar
14 votes

Determinant of a $k \times k$ block matrix

Subtracting the last row of blocks from the first $k-1$ rows of blocks, we obtain $$\begin{bmatrix}A-B & O & O & \dots & O & B-A\\ O & A-B & O & \dots & O & B-A\\ O & O & A-B & \dots & O & B-A\\ \vdo …
Rodrigo de Azevedo's user avatar
4 votes

Nontrivial lower bound on the sum of matrix norms

Let function $f : \mathbb R^{m \times n} \to \mathbb R_0^+$ be defined as follows $$f (\mathrm X) := \| \,\mathrm X \mathrm A^\top \|_\text{F}^2 + \| \,\mathrm X^\top \mathrm A \,\|_\text{F}^2 + \lef …
Rodrigo de Azevedo's user avatar