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We use elementary triangular matrices to obtain some factorization, multiplication, and inversion properties of triangular matrices. We also obtain explicit expressions for the inverses of strict $k$-Hessenberg matrices and banded matrices.…

Rings and Algebras · Mathematics 2015-10-06 Luis Verde-Star

Cut-based directed graph (digraph) clustering often focuses on finding dense within-cluster or sparse between-cluster connections, similar to cut-based undirected graph clustering methods. In contrast, for flow-based clusterings the edges…

Machine Learning · Computer Science 2022-03-04 Koby Hayashi , Sinan G. Aksoy , Haesun Park

In this paper, we consider the symmetric multi-type non-negative matrix tri-factorization problem (SNMTF), which attempts to factorize several symmetric non-negative matrices simultaneously. This can be considered as a generalization of the…

Data Structures and Algorithms · Computer Science 2020-12-14 Rok Hribar , Timotej Hrga , Gregor Papa , Gašper Petelin , Janez Povh , Nataša Pržulj , Vida Vukašinović

Approximate matrix factorization techniques with both nonnegativity and orthogonality constraints, referred to as orthogonal nonnegative matrix factorization (ONMF), have been recently introduced and shown to work remarkably well for…

Optimization and Control · Mathematics 2015-03-19 Filippo Pompili , Nicolas Gillis , P. -A. Absil , François Glineur

We present a fast Jacobi-like algorithm for computing the eigenvalues, and optionally the eigenvectors, of a real normal matrix. The method gains a computational advantage by using Paardekooper's method for skew-symmetric matrices The…

Numerical Analysis · Mathematics 2026-05-27 Simon Mataigne , P. -A. Absil

This paper proposes uni-orthogonal and bi-orthogonal nonnegative matrix factorization algorithms with robust convergence proofs. We design the algorithms based on the work of Lee and Seung [1], and derive the converged versions by utilizing…

Machine Learning · Computer Science 2011-03-17 Andri Mirzal

We propose a simple technique that, if combined with algorithms for computing functions of triangular matrices, can make them more efficient. Basically, such a technique consists in a specific scaling similarity transformation that reduces…

Numerical Analysis · Mathematics 2021-11-18 João R. Cardoso , Amir Sadeghi

This paper is concerned with the reduction of a unitary matrix U to CMV-like shape. A Lanczos--type algorithm is presented which carries out the reduction by computing the block tridiagonal form of the Hermitian part of U, i.e., of the…

Numerical Analysis · Mathematics 2016-07-27 Roberto Bevilacqua , Gianna M. Del Corso , Luca Gemignani

Tensor diagonalization means transforming a given tensor to an exactly or nearly diagonal form through multiplying the tensor by non-orthogonal invertible matrices along selected dimensions of the tensor. It is generalization of approximate…

Numerical Analysis · Computer Science 2016-07-04 Petr Tichavsky , Anh Huy Phan , Andrzej Cichocki

Three algorithms of Gram-Schmidt type are given that produce an orthogonal decomposition of finite $d$-dimensional symmetric, alternating, or Hermitian forms over division rings. The first uses $d^3/3+O(d^2)$ ring operations with very…

Numerical Analysis · Mathematics 2020-11-23 James B. Wilson

We present a simple proof of the factorization of (complex) symmetric matrices into a product of a square matrix and its transpose, and discuss its application in establishing a uniqueness property of certain antilinear operators.

Mathematical Physics · Physics 2007-05-23 Ali Mostafazadeh

In the non-negative matrix factorization (NMF) problem, the input is an $m\times n$ matrix $M$ with non-negative entries and the goal is to factorize it as $M\approx AW$. The $m\times k$ matrix $A$ and the $k\times n$ matrix $W$ are both…

Data Structures and Algorithms · Computer Science 2021-03-09 Moses Charikar , Lunjia Hu

Finding the inverse of a matrix is an open problem especially when it comes to engineering problems due to their complexity and running time (cost) of matrix inversion algorithms. An optimum strategy to invert a matrix is, first, to reduce…

This article studies canonical forms derived from the finest simultaneous block diagonalization of a set of symmetric matrices via congruence. Our technique relies on Harrison's center theory, which is extended from a single higher degree…

Rings and Algebras · Mathematics 2025-12-22 Lishan Fang , Hua-Lin Huang , Jiayan Huang

We describe an explicit algorithm to factorize an even antisymmetric N^2 matrix into triangular and trivial factors. This allows for a straight forward computation of Pfaffians (including their signs) at the cost of N^3/3 flops.

High Energy Physics - Lattice · Physics 2011-09-07 Jürgen Rubow , Ulli Wolff

Theory of matrix factorizations is useful to study hypersurfaces in commutative algebra. To study noncommutative hypersurfaces, which are important objects of study in noncommutative algebraic geometry, we introduce a notion of…

Rings and Algebras · Mathematics 2021-08-05 Izuru Mori , Kenta Ueyama

We describe a second-order accurate approach to sparsifying the off-diagonal blocks in the hierarchical approximate factorizations of sparse symmetric positive definite matrices. The norm of the error made by the new approach depends…

Numerical Analysis · Mathematics 2020-08-05 Bazyli Klockiewicz , Léopold Cambier , Ryan Humble , Hamdi Tchelepi , Eric Darve

The algebra of invariants of d-tuples of n x n skew-symmetric matrices under the action of the orthogonal group by simultaneous conjugation is considered over an infinite field of characteristic different from two. For n=3 and d>0 a minimal…

Representation Theory · Mathematics 2012-07-24 A. A. Lopatin

We propose a new method for computing the eigenvalue decomposition of a dense real normal matrix $A$ through the decomposition of its skew-symmetric part. The method relies on algorithms that are known to be efficiently implemented, such as…

Numerical Analysis · Mathematics 2026-03-31 Simon Mataigne , Kyle A. Gallivan

Given a set of $n$ distinct real numbers, our goal is to form a symmetric, unreduced, tridiagonal, matrix with those numbers as eigenvalues. We give an algorithm which is a stable implementation of a naive algorithm forming the…

Numerical Analysis · Mathematics 2023-11-07 Luca Dieci , Alessandro Pugliese