Results 31 to 40 of about 619,855 (240)

Strictly Hermitian Positive Definite Functions

open access: yes, 2004
Let H be any complex inner product space with inner product . We say that f : C -->C is Hermitian positive definite on H if the matrix $$(f())_{r,s=1}^n \eqno(*)$$ is Hermitian positive definite for all choice of z^1,...,z^n in H, all n.
Pinkus, Allan
core   +4 more sources

A Note on the Derivatives of Isotropic Positive Definite Functions on the Hilbert Sphere [PDF]

open access: yes, 2019
In this note we give a recursive formula for the derivatives of isotropic positive definite functions on the Hilbert sphere. We then use it to prove a conjecture stated by Tr\"ubner and Ziegel, which says that for a positive definite function on the ...
Jäger, Janin
core   +3 more sources

Positive definite functions and Karhunen-Loeve Theorem [PDF]

open access: yes, 2015
Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Μαθηματική Προτυποποίηση σε Σύγχρονες Τεχνολογίες στην ...
Katsimardou, Sofia   +1 more
core   +1 more source

Strictly positive definite functions on compact abelian groups

open access: yes, 2010
We study the Fourier characterisation of strictly positive definite functions on compact abelian groups. Our main result settles the case $G = F \times \mathbb{T}^r$, with $r \in \mathbb{N}$ and $F$ finite.
Emonds, Jan, Fuehr, Hartmut
core   +1 more source

Evaluating functions of positive-definite matrices using colored noise thermostats [PDF]

open access: yes, 2014
Many applications in computational science require computing the elements of a function of a large matrix. A commonly used approach is based on the the evaluation of the eigenvalue decomposition, a task that, in general, involves a computing time that ...
Ceriotti, Michele   +3 more
core   +2 more sources

Positive Definite Norm Dependent Matrices In Stochastic Modeling

open access: yesDemonstratio Mathematica, 2014
Positive definite norm dependent matrices are of interest in stochastic modeling of distance/norm dependent phenomena in nature. An example is the application of geostatistics in geographic information systems or mathematical analysis of varied spatial ...
Kuniewski Sebastian P.   +1 more
doaj   +1 more source

Superconvergence of Semidiscrete Splitting Positive Definite Mixed Finite Elements for Hyperbolic Optimal Control Problems

open access: yesAdvances in Mathematical Physics, 2022
In this paper, we consider semidiscrete splitting positive definite mixed finite element methods for optimal control problems governed by hyperbolic equations with integral constraints.
Yuchun Hua, Yuelong Tang
doaj   +1 more source

Reproducing Kernel Hilbert Spaces of Smooth Fractal Interpolation Functions

open access: yesFractal and Fractional, 2023
The theory of reproducing kernel Hilbert spaces (RKHSs) has been developed into a powerful tool in mathematics and has lots of applications in many fields, especially in kernel machine learning.
Dah-Chin Luor, Liang-Yu Hsieh
doaj   +1 more source

Vertex corrections for positive-definite spectral functions of simple metals [PDF]

open access: yes, 2016
We present a systematic study of vertex corrections in the homogeneous electron gas at metallic densities. The vertex diagrams are built using a recently proposed positive-definite diagrammatic expansion for the spectral function. The vertex function not
Pavlyukh, Y.   +3 more
core   +1 more source

Intrinsic data depth for Hermitian positive definite matrices

open access: yes, 2018
Nondegenerate covariance, correlation and spectral density matrices are necessarily symmetric or Hermitian and positive definite. The main contribution of this paper is the development of statistical data depths for collections of Hermitian positive ...
Chau, Joris   +2 more
core   +1 more source

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