# Questions tagged [matrices]

Questions where the notion matrix has an important or crucial role (for the latter, note the tag matrix-theory for potential use). Matrices appear in various parts of mathematics, and this tag is typically combined with other tags to make the general subject clear, such as an appropriate top-level tag ra.rings-and-algebras, co.combinatorics, etc. and other tags that might be applicable. There are also several more specialized tags concerning matrices.

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### Matrix irreducibility [closed]

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### For a closed, bounded set of matrices, are the corresponding entropies also bounded?

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### Reference for $2$-by-$2$ integer matrices

**5**

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### System of quadratic equations

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### Eigenvalue perturbation Problem

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### Average the covariance matrix over all orthogonal matrices

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### Linearly independent vectors from a matrix product

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### Is it possible for the reduction modulo $p$ of an non-commutative semisimple algebra to be commutative?

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### Complexity of a combination of matrix operations [closed]

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### Distance function on generalized upper half planes

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### Singular values of a matrix that its rows have (1) a tightly bounded angle, and (2) at least some norm

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### Is this “semi-tensor product” something recently invented? Are there other usages of it?

**8**

**1**answer

### On the coefficients that appear in finite groups of matrices with integer entries

**4**

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### Minimal set generators ideal submaximal minors

**1**

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### Eigenvalues of a block matrix with zero diagonal blocks

**10**

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### Are the trace relations among matrices generated by cyclic permutations?

**4**

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### Can all finite-dimensional noncommutative algebras with trace be trace-preserving embedded into matrix rings?

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### maximize quadratic form with respect to cov matrix of multinomial and linear constraint

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### Approximating singular values of the resolvent matrix for a non-Hermitian matrix

**2**

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### Inverting “codimension matrix” for polytopes?

**1**

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### The rank of the Hadamard product

**1**

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### What is the spectral norm of the matrix $\text{diag}(p)-pp^T$?

**0**

**1**answer

### Localizing the intersections of cubics

**3**

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### Operator norm of difference of matrix decompositions

**1**

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### Inverse rotation of Axis/Angle [closed]

**2**

**1**answer

### The “best way” to order unknowns in linear systems

**10**

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### A specific coset decomposition of $\mathrm{GL}_n(\mathbb{C})$

**2**

**1**answer

### Operator norm of triangular truncation on symmetric matrices

**2**

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### System of matrix equations

**4**

**2**answers

### Sufficient conditions for invertibility of a block tridiagonal matrix

**-2**

**1**answer

### Derivative of log determinant [closed]

**4**

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### Hankel determinant of incomplete gamma functions

**1**

**1**answer

### Upper bound on the size of vectors contained in an ellipsoid?

**2**

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### When does a matrix subspace contain a full rank matrix?

**3**

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### Subalgebras of the Temperley-Lieb algebra

**1**

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### Is trace of a slice of an elementary function of a matrix also elementary?

**1**

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### Is there an efficient way to do semidefinite programming with a Lyapunov equation constraint?

**2**

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### growth of the permanent of some band matrix

**1**

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### Matrix equation involving quadratic form

**2**

**1**answer

### Judge a special positive definite matrix in probability

**3**

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### The covariance matrix of quadratic form, without normal assumption

**1**

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### Growth of the number of columns $j=1,\dotsc,p$ such that $\|Ae_j\|_1 > p^\alpha$ for symmetric $A$ with bounded spectrum?

**3**

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### Stability of matrix equation

**9**

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### Lower eigenvectors of nonnegative matrices with zero trace

**5**

**1**answer

### Do there exist positive definite matrices $A$ and $B$ satisfying this condition?

**3**

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### Multiplication of two Pauli string

**4**

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### On the real and finite field rank of a $0/1$ matrix - I

**1**

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### If the direct sum of $L$ and $M$ has a pseudoinverse, then do $L$ and $M$ have pseudoinverses?

**2**

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### Block circulant matrix with some non-zero minors

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