Results 21 to 30 of about 49,656 (213)

A counterexample to the Drury permanent conjecture

open access: yesSpecial Matrices, 2017
We offer a counterexample to a conjecture concerning the permanent of positive semidefinite matrices. The counterexample is a 4 × 4 complex correlation matrix.
Hutchinson George
doaj   +1 more source

Existence and Uniqueness of the Positive Definite Solution for the Matrix Equation X=Q+A∗(X^−C)−1A

open access: yesAbstract and Applied Analysis, 2013
We consider the nonlinear matrix equation X=Q+A∗(X^−C)−1A, where Q is positive definite, C is positive semidefinite, and X^ is the block diagonal matrix defined by X^=diag(X,X,…,X).
Dongjie Gao
doaj   +1 more source

Riccati equation and metric geometric means of positive semidefinite matrices involving semi-tensor products

open access: yesAIMS Mathematics, 2023
We investigate the Riccati matrix equation $ X A^{-1} X = B $ in which the conventional matrix products are generalized to the semi-tensor products $ \ltimes $. When $ A $ and $ B $ are positive definite matrices satisfying the factor-dimension condition,
Pattrawut Chansangiam, Arnon Ploymukda
doaj   +1 more source

A time-dependent regularization of the Redfield equation

open access: yesSciPost Physics, 2023
We introduce a new regularization of the Redfield equation based on a replacement of the Kossakowski matrix with its closest positive semidefinite neighbor.
Antonio D'Abbruzzo, Vasco Cavina, Vittorio Giovannetti
doaj   +1 more source

Bounds of the logarithmic mean [PDF]

open access: yes, 2013
We give tight bounds for logarithmic mean. We also give new Frobenius norm inequalities for two positive semidefinite matrices. In addition, we give some matrix inequalities on matrix power mean.Comment: The second assertion in (i) of Proposition 5.2 was
Furuichi, Shigeru, Yanagi, Kenjiro
core   +2 more sources

Efficient Positive Semidefinite Matrix Approximation by Iterative Optimisations and Gradient Descent Method

open access: yesRisks
We devise two algorithms for approximating solutions of PSDisation, a problem in actuarial science and finance, to find the nearest valid correlation matrix that is positive semidefinite (PSD).
Vali Asimit   +3 more
doaj   +1 more source

Separability for mixed states with operator Schmidt rank two [PDF]

open access: yesQuantum, 2019
The operator Schmidt rank is the minimum number of terms required to express a state as a sum of elementary tensor factors. Here we provide a new proof of the fact that any bipartite mixed state with operator Schmidt rank two is separable, and can be ...
Gemma De las Cuevas   +2 more
doaj   +1 more source

Positive semidefinite matrix supermartingales

open access: yesElectronic Journal of Probability
EJP.
Wang, Hongjian, Ramdas, Aaditya
openaire   +2 more sources

Fast implementation for semidefinite programs with positive matrix completion [PDF]

open access: yesOptimization Methods and Software, 2015
Solving semidefinite programs (SDP) in a short time is the key to managing various mathematical optimization problems. The matrix-completion primal-dual interior-point method (MC-PDIPM) extracts a sparse structure of input SDP by factorizing the variable matrices. In this paper, we propose a new factorization based on the inverse of the variable matrix
Makoto Yamashita, Kazuhide Nakata
openaire   +2 more sources

Positive Maps and Separable Matrices

open access: yes, 2016
A linear map between real symmetric matrix spaces is positive if all positive semidefinite matrices are mapped to positive semidefinite ones. A real symmetric matrix is separable if it can be written as a summation of Kronecker products of positive ...
Nie, Jiawang, Zhang, Xinzhen
core   +1 more source

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