Problem Based Benchmark Suite (2020)

Nbody Force Calculation (NBODY):

Given n points in 3 dimensions calculate the gravitational force vector on each point due to all other points. This force vector can be an approximation. For this benchmakr we use a gravitational constant of 1 giving the force between two particles located at r₁ and r₂ as : F₁₂ = m₁ m₂ (r₂ - r₁)/ |(r₂ - r₁)|³.

Input and Output File Formats

The input and output files need to be in the 3d points file format. The input file is a set of points specified by their location. In the current version all weights are assumed to be unit. The output file specifies the force vector on each point and therefore should have the same number of entries as the input.

Default Input Distributions

Each distribution should be run for n=1,000,000. The weights used for average time are given in parentheses. In all cases the accuracy of the forces need to be within an error bound of 10^-6, i.e., |(F - F')/|F|| < 10^-6, where F is the actual force and F' the reported force.

• (1) Points selected at random uniformly within a unit sphere.

  uniform -s -d 3 <n> <filename>

• (1) Points selected at random from the Plummer distribution.

  plummer -d 3 <n> <filename>

• (1) Points selected at random uniformly on the surface of a unit sphere.

  uniform -S -d 3 <n> <filename>