Results 71 to 80 of about 33,726 (205)

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

Risks
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, Runshi Wang, Feng Zhou, Rui Zhu   +3 more
doaj   +1 more source

Application of semidefinite programming to truss design optimization / Santvaros optimizavimo uždavinių sprendimas taikant pusiau apibrėžtą programavimą

Mokslas: Lietuvos Ateitis, 2015
Semidefinite Programming (SDP) is a fairly recent way of solving optimization problems which are becoming more and more important in our fast moving world. It is a minimization of linear function over the intersection of the cone of positive semidefinite
Rasa Giniūnaitė
doaj   +1 more source

Spatial Image Gradient Estimation From the Diffusion MRI Profile

Magnetic Resonance in Medicine, Volume 95, Issue 5, Page 2980-2991, May 2026.
ABSTRACT Purpose In the course of diffusion, water molecules encounter varying values for the relaxation‐time properties of the underlying tissue. This factor, which has rarely been accounted for in diffusion MRI (dMRI), is modeled in this work, allowing for the estimation of the gradient of relaxation‐time properties from the dMRI signal. Methods With
Iman Aganj, Thorsten Feiweier, John E. Kirsch, Bruce R. Fischl, Andre J. van der Kouwe   +4 more
wiley   +1 more source

Semidefinite Relaxation Method for Target Localization by MIMO Radar Using Bistatic Ranges

International Journal of Distributed Sensor Networks, 2014
We address the target localization problem by using bistatic range (BR) measurements in widely separated multiple-input multiple-output (MIMO) radar network.
Bin Sun, Haowen Chen, Xizhang Wei, Xiang Li   +3 more
doaj   +1 more source

Entrywise transforms preserving matrix positivity and nonpositivity

Journal of the London Mathematical Society, Volume 113, Issue 5, May 2026.
Abstract We characterize real and complex functions which, when applied entrywise to square matrices, yield a positive definite matrix if and only if the original matrix is positive definite. We refer to these transformations as sign preservers. Compared to the classical work on entrywise preservers by Schoenberg and others, we completely resolve this ...
Dominique Guillot, Himanshu Gupta, Prateek Kumar Vishwakarma, Chi Hoi Yip   +3 more
wiley   +1 more source

Approximating Semidefinite Packing Programs [PDF]

SIAM Journal on Optimization, 2011
In this paper we define semidefinite packing programs and describe an algorithm to approximately solve these problems. Semidefinite packing programs arise in many applications such as semidefinite programming relaxations for combinatorial optimization problems, sparse principal component analysis, and sparse variance unfolding techniques for dimension ...
Garud Iyengar, David J. Phillips, Clifford Stein 0001   +2 more
openaire   +1 more source

Data‐Based Refinement of Parametric Uncertainty Descriptions

International Journal of Robust and Nonlinear Control, Volume 36, Issue 6, Page 3210-3228, April 2026.
ABSTRACT We consider dynamical systems with a linear fractional representation involving parametric uncertainties which are either constant or varying with time. Given a finite‐horizon input‐state or input‐output trajectory of such a system, we propose a numerical scheme which iteratively improves the available knowledge about the involved constant ...
Tobias Holicki, Carsten W. Scherer
wiley   +1 more source

A paradox in bosonic energy computations via semidefinite programming relaxations

New Journal of Physics, 2013
We show that the recent hierarchy of semidefinite programming relaxations based on non-commutative polynomial optimization and reduced density matrix variational methods exhibits an interesting paradox when applied to the bosonic case: even though it can
M Navascués, A García-Sáez, A Acín, S Pironio, M B Plenio   +4 more
doaj   +1 more source

Flexible and Interpretable Modeling of Overlapping Exposure Risks in Self‐Controlled Case Series Analysis

Statistics in Medicine, Volume 45, Issue 8-9, April 2026.
ABSTRACT The self‐controlled case series (SCCS) method is frequently employed to explore the relationship between transient exposures and subsequent health events, utilizing data from individuals who have experienced the event of interest. Conventional spline‐based SCCS models typically do not account for overlapping exposure periods and fail to ...
Xuezhixing Zhang, Paul Milligan, Yin Bun Cheung   +2 more
wiley   +1 more source

Correcting for finite statistics effects in a quantum steering experiment

Physical Review Research
Verifying entanglement between parties is essential for creating secure quantum communication. However, finite statistics can lead to false positive outcomes in any tests for entanglement.
Sophie Engineer, Ana C. S. Costa, Alexandre C. Orthey, Jr., Xiaogang Qiang, Jianwei Wang, Jeremy L. O'Brien, Jonathan C. F. Matthews, Will McCutcheon, Roope Uola, Sabine Wollmann   +9 more
doaj   +1 more source