README

PROJECT STATUS: complete


Contained in this directory is code for simulating the n-body problem using the 
barnes-hut tree algorithm.The barnes hut cuda code is loosely based on the openCL code by Benjamin Neukom https://github.com/bneukom/gpu-nbody and the paper "An Efficient CUDA Implementation of the 
Tree-Based Barnes Hut n-Body Algorithm" by Martin Burtscher and Keshav Pingali.


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         Dependencies
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This software requires the Nvidia CUDA toolkit installed on a system with a CUDA capable device 
(gcc must also be installed).To install CUDA see https://developer.nvidia.com/cuda-downloads and the CUDA Quick Start Guide. 



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               Compiling
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Before compiling see notes below. To compile the code simply type in a terminal:

make clean
make build



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              Running        
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To run the barnes-hut algorithm with benchmarks for 500 iterations, simply type:

./main -barnes-hut -benchmark -iterations=500

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             Notes
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Currently you must manually set the number of particles (numbodies) in main.cpp and then ensure that 
the blockSize variable in kernels.cu and the blockSize and gridSize variables in particle_cuda.cu 
matches. For example if you set numbodies = 64*64 in main.cpp, then you must also set blockSize = 64 in 
kernels.cu, and blockSize = 64, gridSize = 64, in particle_cuda.cu.