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We propose an efficient algorithm for the evaluation of the potential and its gradient of gravitational/electrostatic $N$-body systems, which we call particle mesh multipole method (PMMM or PM$^3$). PMMM can be understood both as an…

Instrumentation and Methods for Astrophysics · Physics 2014-10-20 Keigo Nitadori

I describe a modification to the original Fast Multipole Method (FMM) of Greengard & Rokhlin that approximates the gravitation field of an FMM cell as a small uniform grid (a "gridlet") of effective masses. The effective masses on a gridlet…

Computational Physics · Physics 2019-07-31 Nickolay Y. Gnedin

We discuss the performance characteristics of using the modification of the tree code suggested by Barnes \citep{1990JCoPh..87..161B} in the context of the TreePM code. The optimisation involves identifying groups of particles and using…

Astrophysics · Physics 2015-05-13 Nishikanta Khandai , J. S. Bagla

We describe the TreePM method for carrying out large N-Body simulations to study formation and evolution of the large scale structure in the Universe. This method is a combination of Barnes and Hut tree code and Particle-Mesh code. It…

Astrophysics · Physics 2009-10-31 J. S. Bagla

Direct $N$-body simulations of star clusters are accurate but expensive, largely due to the numerous $\mathcal{O} (N^2)$ pairwise force calculations. To solve the post-million-body problem, it will be necessary to use approximate force…

Astrophysics of Galaxies · Physics 2021-08-24 Diptajyoti Mukherjee , Qirong Zhu , Hy Trac , Carl L. Rodriguez

To assess how future progress in gravitational microlensing computation at high optical depth will rely on both hardware and software solutions, we compare a direct inverse ray-shooting code implemented on a graphics processing unit (GPU)…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 N. F. Bate , C. J. Fluke , B. R. Barsdell , H. Garsden , G. F. Lewis

We present a gravitational hierarchical N-body code that is designed to run efficiently on Graphics Processing Units (GPUs). All parts of the algorithm are executed on the GPU which eliminates the need for data transfer between the Central…

Instrumentation and Methods for Astrophysics · Physics 2012-04-12 Jeroen Bédorf , Evghenii Gaburov , Simon Portegies Zwart

In this paper, we present a new hybrid algorithm for the time integration of collisional N-body systems. In this algorithm, gravitational force between two particles is divided into short-range and long-range terms, using a…

Earth and Planetary Astrophysics · Physics 2015-05-27 Shoichi Oshino , Yoko Funato , Junichiro Makino

We present Particle-Particle-Particle-Mesh (PPPM) and Tree Particle-Mesh (TreePM) implementations on GRAPE-5 and GRAPE-6A systems, special-purpose hardware accelerators for gravitational many-body simulations. In our PPPM and TreePM…

Astrophysics · Physics 2015-06-24 Kohji Yoshikawa , Toshiyuki Fukushige

We propose a hybrid tree algorithm for reducing calculation and communication cost of collision-less N-body simulations. The concept of our algorithm is that we split interaction force into two parts: hard-force from neighbor particles and…

Instrumentation and Methods for Astrophysics · Physics 2014-06-25 Tsuyoshi Watanabe , Naohito Nakasato

We have developed a gravity solver based on combining the well developed Particle-Mesh (PM) method and TREE methods. It is designed for and has been implemented on parallel computer architectures. The new code can deal with tens of millions…

Astrophysics · Physics 2009-10-22 Guohong Xu

There are many methods used to compute the classical gravitational field in astrophysical simulation codes. With the exception of the typically impractical method of direct computation, none ensure conservation of angular momentum to…

Instrumentation and Methods for Astrophysics · Physics 2017-08-23 Dominic C. Marcello

The Fast Multipole Method (FMM) computes pairwise interactions between particles with an efficiency that scales linearly with the number of particles. The method works by grouping particles based on their spatial distribution and…

Computational Physics · Physics 2025-08-05 He Zhang

We describe a parallel, cosmological N-body code based on a hybrid scheme using the particle-mesh (PM) and Barnes-Hut (BH) oct-tree algorithm. We call the algorithm GOTPM for Grid-of-Oct-Trees-Particle-Mesh. The code is parallelized using…

Astrophysics · Physics 2015-06-24 John Dubinski , Juhan Kim , Changbom Park , Robin Humble

I describe here the performance of a parallel treecode with individual particle timesteps. The code is based on the Barnes-Hut algorithm and runs cosmological N-body simulations on parallel machines with a distributed memory architecture…

Astrophysics · Physics 2009-11-07 R. Valdarnini

The notion of well-separated sets is crucial in fast multipole methods as the main idea is to approximate the interaction between such sets via cluster expansions. We revisit the one-parameter multipole acceptance criterion in a general…

Numerical Analysis · Mathematics 2011-08-11 Stefan Engblom

Computer simulation with Monte Carlo is an important tool to investigate the function and equilibrium properties of many systems with biological and soft matter materials solvable in solvents. The appropriate treatment of long-range…

Computational Physics · Physics 2015-06-15 Zecheng Gan , Zhenli Xu

We investigate a hybrid numerical algorithm aimed at the large-scale cosmological N-body simulation for the on-going and the future high precious sky surveys. It makes use of a truncated Fast Multiple Method (FMM) for short-range gravity,…

Computational Physics · Physics 2021-01-13 Qiao Wang

Fast multipole methods have O(N) complexity, are compute bound, and require very little synchronization, which makes them a favorable algorithm on next-generation supercomputers. Their most common application is to accelerate N-body…

Numerical Analysis · Computer Science 2012-03-06 Hatem Ltaief , Rio Yokota

We propose new methods for Support Vector Machines (SVMs) using tree architecture for multi-class classi- fication. In each node of the tree, we select an appropriate binary classifier using entropy and generalization error estimation, then…

Machine Learning · Computer Science 2017-08-29 Pittipol Kantavat , Boonserm Kijsirikul , Patoomsiri Songsiri , Ken-ichi Fukui , Masayuki Numao