Results 51 to 60 of about 41,274 (203)
A class of positive semidefinite matrices
Linear Algebra and its Applications, 1987 It is a known fact that, given a positive definite matrix \(y_{ij}\), the ``standardized'' matrix \(y_{ij}(y_{ii}y_{jj})^{-}\) is again positive definite. The authors investigate more general standardization methods of the form \(a_{ij}(\alpha)y_{ij}\) where \(\alpha\) is a positive number and \(a_{ij}(\alpha)=(\phi (x_ i,\alpha)+\phi (x_ j,\alpha))^{-}
Russell, A.M., Upton, C.J.F.
openaire +2 more sources
Evaluating Forecasts at Multiple Horizons: An Extension of the Diebold–Mariano Approach
Journal of Forecasting, EarlyView.ABSTRACT Forecast accuracy tests are fundamental tools for comparing competing predictive models. The widely used Diebold–Mariano (DM) test assesses whether differences in forecast errors are statistically significant. However, its standard form is limited to pairwise comparisons at a single forecast horizon.
Andrew Grant +2 more
wiley +1 more source
Generalized Randić Estrada Indices of Graphs
Mathematics, 2022 Let G be a simple undirected graph on n vertices. V. Nikiforov studied hybrids of AG and DG and defined the matrix AαG for every real α∈[0,1] as AαG=αDG+(1−α)AG.
Eber Lenes +3 more
doaj +1 more source
, 2012 We consider a short rate model, driven by a stochastic process on the cone of positive semidefinite matrices.
ALESSANDRO GNOATTO +4 more
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Edge‐Length Preserving Embeddings of Graphs Between Normed Spaces
Journal of Graph Theory, EarlyView.ABSTRACT The concept of graph embeddability, initially formalized by Belk and Connelly and later expanded by Sitharam and Willoughby, extends the question of embedding finite metric spaces into a given normed space. A finite simple graph G = ( V , E ) $G=(V,E)$ is said to be ( X , Y ) $(X,Y)$‐embeddable if any set of induced edge lengths from an ...
Sean Dewar +3 more
wiley +1 more source
Adaptation of Symmetric Positive Semi-Definite Matrices for the Analysis of Textured Images
Cybernetics and Information Technologies, 2018 This paper addresses the analysis of textured images using the symmetric positive semi-definite matrix. In particular, a field of symmetric positive semi-definite matrices is used to estimate the structural information represented by the local ...
Akl Adib
doaj +1 more source
Hyperbolicity cones of elementary symmetric polynomials are spectrahedral [PDF]
, 2013 We prove that the hyperbolicity cones of elementary symmetric polynomials are spectrahedral, i.e., they are slices of the cone of positive semidefinite matrices.
Brändén, Petter
core +1 more source
International Journal of Mechanical System Dynamics, EarlyView.ABSTRACT Hydraulic manipulators exhibit strong coupling, pronounced nonlinearities, and significant modeling uncertainties, which hinder high‐precision motion control. This paper proposes a finite‐time disturbance observer–based nonlinear robust adaptive control (RAC‐FTDO) framework enhanced by a physically consistent dynamic parameter identification ...
Tianyu Gao +3 more
wiley +1 more source
Simply Exponential Approximation of the Permanent of Positive Semidefinite Matrices
, 2017 We design a deterministic polynomial time $c^n$ approximation algorithm for the permanent of positive semidefinite matrices where $c=e^{\gamma+1}\simeq 4.84$.
Anari, Nima +3 more
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Conditions for Existence of Dual Certificates in Rank-One Semidefinite Problems [PDF]
, 2014 Several signal recovery tasks can be relaxed into semidefinite programs with rank-one minimizers. A common technique for proving these programs succeed is to construct a dual certificate.
Hand, Paul
core +1 more source