Filters








398,819 Hits in 5.4 sec

Approximation algorithms for spreading points

Sergio Cabello
2007 Journal of Algorithms  
In the L ∞ metric, we give a 2-approximation algorithm running in O(n √ n log 2 n) time.  ...  In the L 2 metric, we give a quadratic time algorithm that gives an 8 3 -approximation in general, and a ∼ 2.2393-approximation when all the disks are congruent.  ...  Thanks again to Marc for correcting the draft version and pointing out Lemma 6, which improved the previous running time.  ... 
doi:10.1016/j.jalgor.2004.06.009 fatcat:yulpwf7fl5fhhmakrmmfjxjqkm

Approximation Algorithms for Spreading Points [chapter]

Sergio Cabello
2005 Lecture Notes in Computer Science  
In the L ∞ metric, we give a 2-approximation algorithm running in O(n √ n log 2 n) time.  ...  In the L 2 metric, we give a quadratic time algorithm that gives an 8 3 -approximation in general, and a ∼ 2.2393-approximation when all the disks are congruent.  ...  Thanks again to Marc for correcting the draft version and pointing out Lemma 6, which improved the previous running time.  ... 
doi:10.1007/978-3-540-31833-0_9 fatcat:wcftq5muvrbd3nnnm33zwopp3a

A fine-grained parallelization of the immersed boundary method [article]

Andrew Kassen and Varun Shankar and Aaron L Fogelson
2021 arXiv   pre-print
We present new algorithms for the parallelization of Eulerian-Lagrangian interaction operations in the immersed boundary method.  ...  We present strong and weak scaling tests on problems involving scattered points and elastic structures. Our tests show that our algorithms exhibit near-ideal scaling on both multicore CPUs and GPUs.  ...  Funding The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Science Foundation [  ... 
arXiv:2012.06646v3 fatcat:2g3r6laobzberb3ffruecejthu

On Approximate Geometric k -Clustering

J. Matoušek
2000 Discrete & Computational Geometry  
Suppose there is an algorithm A that, for a given ε>0, k k 0 , and an n-point multiset X' R d with points lying on an integer grid of size O(n 3 /ε), finds an (1+ε)-approximately optimal k-clustering of  ...  Then a (1+ε)approximately optimal k 0 clustering for an arbitrary n-point subset X R d can be computed with O(n log n) preprocessing and with at most C calls to algorithm A, with various at most n-point  ...  Correctness • For any k-tuple (c 1 ,…,c k ), the algorithm generates a tuple that is ε-near Running Time • All range queries are done by approximate range searching in time O(log n) • Approximate Voronoi  ... 
doi:10.1007/s004540010019 fatcat:4iu7zt3oofhztbr72unxnkcd2a

The grid-dose-spreading algorithm for dose distribution calculation in heavy charged particle radiotherapy

Nobuyuki Kanematsu, Shunsuke Yonai, Azusa Ishizaki
2008 Medical Physics (Lancaster)  
A new variant of the pencil-beam (PB) algorithm for dose distribution calculation for radiotherapy with protons and heavier ions, the grid-dose spreading (GDS) algorithm, is proposed.  ...  The GDS algorithm is intrinsically faster than conventional PB algorithms due to approximations in convolution integral, where physical calculations are decoupled from simple grid-to-grid energy transfer  ...  In other words, the planar spreading is approximately resolved into the three uncorrelated orthogonal spreading by σ x = 3.9 mm, σ y = 4.5 mm, and σ z = 2.3 mm, which has deformed the point-spreading function  ... 
doi:10.1118/1.2829878 pmid:18383681 fatcat:3imcze3h5fegrpjn6siicqwyci

On the mathematic modeling of non-parametric curves based on cubic Bézier curves [article]

Ha Jong Won, Choe Chun Hwa, Li Kum Song
2014 arXiv   pre-print
This paper presents a method which determines control points for B\'ezier curves approximating segments of obtained image outline(non-parametric curve) by using the properties of cubic B\'ezier curves.  ...  Proposed method is a technique to determine the control points that has generality and reduces the error of the B\'ezier curve approximation.  ...  The proposed technique can be very useful in various applications that involve problems of cubic Bézier spline approximation for given nonparametric curve such as outline shapes of natural objects.  ... 
arXiv:1411.6365v1 fatcat:7vj7e5h53ze55ozvi3v67gqs7e

A Covariance Fitting Approach to Parametric Localization of Multiple Incoherently Distributed Sources

S. Shahbazpanahi, S. Valaee, A.B. Gershman
2004 IEEE Transactions on Signal Processing  
In this paper, a new algorithm for parametric localization of multiple incoherently distributed sources is presented.  ...  This algorithm is based on an approximation of the array covariance matrix using central and noncentral moments of the source angular power densities.  ...  Besson, who provided the access to his MATLAB code for the EXIP algorithm. The authors also wish to thank Dr. M.  ... 
doi:10.1109/tsp.2003.822352 fatcat:knlp5nhjtfhbxls2kkgsgcztdi

Experience generalization for concurrent reinforcement learners

Carlos H. C. Ribeiro, Renê Pegoraro, Anna H. Reali Costa
2002 Proceedings of the first international joint conference on Autonomous agents and multiagent systems part 3 - AAMAS '02  
We investigate the use of experience generalization for increasing the rate of convergence of RL algorithms, and contribute a new learning algorithm, Minimax-QS, which incorporates experience generalization  ...  to the Minimax-Q algorithm.  ...  point, that would mean that T mqs t also approximates T mq at Q.  ... 
doi:10.1145/545104.545106 fatcat:nsbqr6mjezh7fbgxyhttbgmrcy

Experience generalization for concurrent reinforcement learners

Carlos H. C. Ribeiro, Renê Pegoraro, Anna H. Reali Costa
2002 Proceedings of the first international joint conference on Autonomous agents and multiagent systems part 3 - AAMAS '02  
We investigate the use of experience generalization for increasing the rate of convergence of RL algorithms, and contribute a new learning algorithm, Minimax-QS, which incorporates experience generalization  ...  to the Minimax-Q algorithm.  ...  point, that would mean that T mqs t also approximates T mq at Q.  ... 
doi:10.1145/545056.545106 dblp:conf/atal/RibeiroPC02 fatcat:zk22ii7shvg4pdbkbi4vo7apvy

k-Center Clustering with Outliers in the Sliding-Window Model [article]

Mark de Berg and Morteza Monemizadeh and Yu Zhong
2021 arXiv   pre-print
The algorithm works for the case where the points come from a space of bounded doubling dimension and it maintains a set S(t) such that an optimal solution on S(t) gives a (1+ε)-approximate solution on  ...  The algorithm is deterministic and uses O((kz/ε^d)logσ) storage, where d is the doubling dimension of the underlying space and σ is the spread of the points in the stream.  ...  For any spread σ ⩾ (3kz/ε) 2 , there is a problem instance of spread σ that requires Alg to store Ω((kz log σ)/ε) points.  ... 
arXiv:2109.11853v1 fatcat:xtxl7vp6ord7vowdvxnajbottu

A Memetic Procedure for Global Multi-Objective Optimization [article]

Matteo Lapucci and Pierluigi Mansueto and Fabio Schoen
2022 arXiv   pre-print
The resulting algorithm, which we call Non-dominated Sorting Memetic Algorithm (NSMA), besides enjoying interesting theoretical properties, excels in all of the numerical tests we performed on several,  ...  main classes: evolutionary methods, which are usually very good at exploring the feasible region and retrieving good solutions even in the nonconvex case, and descent methods, which excel in efficiently approximating  ...  So, every point produced by FMOPG could be useful to obtain good and spread Pareto front approximations.  ... 
arXiv:2201.11444v1 fatcat:ywecdbburvdr7igdy5hf25z6bu

Dynamic sensitivities and Initial Margin via Chebyshev Tensors [article]

Mariano Zeron, Ignacio Ruiz
2020 arXiv   pre-print
We obtain high accuracy and computational gains for FX swaps and Spread Options.  ...  For the Spread Option, maximum relative error for dynamic deltas was 10.7%, mostly due to the numerical noise of the underlying function being approximated.  ...  One for a FX Swap; the other for a European Spread Option.  ... 
arXiv:2011.04544v1 fatcat:is4e2yjqkjcv7jkhei7h6pox3i

An Efficient, Approximate Path-Following Algorithm For Elastic Net-Based Nonlinear Spike Enhancement

Max Little
2014 Zenodo  
Input signal (black square) is the starting point for the approximate path-following algorithm, which comes close to the minimizer for (1) (red circle) obtained by solving the quadratic programming problem  ...  Similarly, although the approximate algorithm can achieve good performance at low noise spread, because it only approximately minimizes (1), it has variable performance that might require controlled adaptation  ... 
doi:10.5281/zenodo.44098 fatcat:xki5imychbglbmsshxfn2ncvv4

Practical Rendering of Multiple Scattering Effects in Participating Media [article]

Simon Premoze, Michael Ashikhmin, Jerry Tessendorf, Ravi Ramamoorthi, Shree Nayar
2004 Symposium on Rendering  
We show an expression for the point spread function that captures blurring of radiance due to multiple scattering.  ...  We develop a general framework for incorporating this point spread function, while considering inhomogeneous media - this framework could also be used with other analytic multiple scattering models.  ...  Acknowledgements We would like to thank Jerry Tessendorf for helpful discussions of the path integral formulation.  ... 
doi:10.2312/egwr/egsr04/363-374 fatcat:xu6vomo5qjdsvpgfqvwkwebwyq

Calculations of HREM Image Intensity Using Monte Carlo Integration

L Y Chang, R R Meyer, A I Kirkland
2005 Microscopy and Microanalysis  
The computation for these algorithms can therefore be extremely demanding and hence some approximations regarding partial coherence effects have been introduced making these algorithms computationally  ...  Most image restoration algorithms involve the linear imaging approximation [4, 5] , which has the advantage of computational efficiency.  ...  The computation for these algorithms can therefore be extremely demanding and hence some approximations regarding partial coherence effects have been introduced making these algorithms computationally  ... 
doi:10.1017/s1431927605503751 fatcat:y2f2yd7efraitl72xxt64fftvi
« Previous Showing results 1 — 15 out of 398,819 results