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We present a method for extracting actions, angles and frequencies from an orbit's time series. The method recovers the generating function that maps an analytic phase-space torus to the torus to which the orbit is confined by…

Astrophysics of Galaxies · Physics 2015-06-18 Jason L. Sanders , James Binney

We give an algorithm for the economical calculation of angles and actions for stars in axisymmetric potentials. We test the algorithm by integrating orbits in a realistic model of the Galactic potential, and find that, even for orbits…

Astrophysics of Galaxies · Physics 2015-06-05 James Binney

We describe a method for calculating action-angle variables in axisymmetric galactic potentials using Birkhoff normalization, a technique from Hamiltonian perturbation theory. An advantageous feature of this method is that it yields…

Astrophysics of Galaxies · Physics 2024-04-29 Sam Hadden

We show how rational function approximations to the logarithm, such as $\log z \approx (z^2 - 1)/(z^2 + 6z + 1)$, can be turned into fast algorithms for approximating the determinant of a very large matrix. We empirically demonstrate that…

Data Structures and Algorithms · Computer Science 2024-05-07 Thomas Colthurst , Srinivas Vasudevan , James Lottes , Brian Patton

Action-angle coordinates are an essential tool for understanding the properties of the six dimensional phase space involved in orbits of stars in galactic potentials. A new method, which does not require specific knowledge of a generating…

Astrophysics of Galaxies · Physics 2014-07-08 Michael F. J. Fox

We propose a planning and control approach to physics-based manipulation. The key feature of the algorithm is that it can adapt to the accuracy requirements of a task, by slowing down and generating `careful' motion when the task requires…

Robotics · Computer Science 2019-01-23 Wisdom C. Agboh , Mehmet R. Dogar

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

Our previously-developed calculational method (the partial wave cutoff method) is employed to evaluate explicitly scalar one-loop effective actions in a class of radially symmetric background gauge fields. Our method proves to be…

High Energy Physics - Theory · Physics 2008-11-26 Gerald V. Dunne , Jin Hur , Choonkyu Lee , Hyunsoo Min

We use a set of Stackel potentials to obtain a local approximation for an effective third integral in axisymmetric systems. We present a study on the feasibility and effectiveness of this approach. We have applied it to three trial…

Astrophysics · Physics 2009-10-31 V. De Bruyne , F. Leeuwin , H. Dejonghe

We introduce the "ACTIONFINDER", a deep learning algorithm designed to transform a sample of phase-space measurements along orbits in a static potential into action and angle coordinates. The algorithm finds the mapping from positions and…

Astrophysics of Galaxies · Physics 2023-03-06 Rodrigo Ibata , Foivos Diakogiannis , Benoit Famaey , Giacomo Monari

3D action recognition was shown to benefit from a covariance representation of the input data (joint 3D positions). A kernel machine feed with such feature is an effective paradigm for 3D action recognition, yielding state-of-the-art…

Computer Vision and Pattern Recognition · Computer Science 2017-10-05 Jacopo Cavazza , Pietro Morerio , Vittorio Murino

We survey key techniques and results from approximation theory in the context of uniform approximations to real functions such as e^{-x}, 1/x, and x^k. We then present a selection of results demonstrating how such approximations can be used…

Data Structures and Algorithms · Computer Science 2013-09-20 Sushant Sachdeva , Nisheeth Vishnoi

Given the present distribution of mass tracing objects in an expanding universe, we develop and test a fast method for recovering their past orbits using the least action principle. In this method, termed FAM for Fast Action Minimization,…

Astrophysics · Physics 2009-10-31 Adi Nusser , Enzo Branchini

We discuss the effective potential of the conformal factor in the effective average action approach to Quantum Einstein Gravity. Without invoking any truncation or other approximations we show that if the theory has has a non-Gaussian…

High Energy Physics - Theory · Physics 2010-11-11 Jan-Eric Daum , Martin Reuter

We present a system for concurrent activity recognition. To extract features associated with different activities, we propose a feature-to-activity attention that maps the extracted global features to sub-features associated with individual…

Computer Vision and Pattern Recognition · Computer Science 2018-12-10 Yanyi Zhang , Xinyu Li , Kaixiang Huang , Yehan Wang , Shuhong Chen , Ivan Marsic

We propose a general algorithm for approximating nonstandard Bayesian posterior distributions. The algorithm minimizes the Kullback-Leibler divergence of an approximating distribution to the intractable posterior distribution. Our method…

Computation · Statistics 2014-07-29 Tim Salimans , David A. Knowles

Motion prediction in unstructured environments is a difficult problem and is essential for safe and efficient human-robot space sharing and collaboration. In this work, we focus on manipulation movements in environments such as homes,…

Robotics · Computer Science 2020-07-21 Philipp Kratzer , Niteesh Balachandra Midlagajni , Marc Toussaint , Jim Mainprice

We propose a new nonconforming finite element algorithm to approximate the solution to the elliptic problem involving the fractional Laplacian. We first derive an integral representation of the bilinear form corresponding to the variational…

Numerical Analysis · Mathematics 2018-12-20 Andrea Bonito , Wenyu Lei , Joseph E. Pasciak

We propose a variational method to solve all three estimation problems for nonlinear stochastic dynamical systems: prediction, filtering, and smoothing. Our new approach is based upon a proper choice of cost function, termed the {\it…

Data Analysis, Statistics and Probability · Physics 2007-05-23 Gregory L. Eyink

We propose a new cross-conv algorithm for approximate computation of convolution in different low-rank tensor formats (tensor train, Tucker, Hierarchical Tucker). It has better complexity with respect to the tensor rank than previous…

Numerical Analysis · Mathematics 2016-09-07 M. V. Rakhuba , I. V. Oseledets
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