Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Nested Grid Particle-Mesh Code for High Resolution Simulations of
  Gravitational Instability in Cosmology   I describe a nested-grid particle-mesh (NGPM) code designed to study
gravitational instability in three-dimensions. The code is based upon a
standard PM code. Within the parent grid I am able to define smaller sub-grids
allowing us to substantially extend the dynamical range in mass and length. I
treat the fields on the parent grid as background fields and utilize a one-way
interactive meshing. Waves on the coarse parent grid are allowed to enter and
exit the subgrid, but waves from the subgrid are precluded from effecting the
dynamics of the parent grid. On the parent grid the potential is computed using
a standard multiple Fourier transform technique. On the subgrid I use a Fourier
transform technique to compute the subgrid potential at high resolution. I
impose quasi-isolated boundary conditions on the subgrid using the standard
method for generating isolated boundary conditions, but rather than using the
isolated Green function I use the Ewald method to compute a Green function on
the subgrid which possesses the full periodicity of the parent grid. I present
a detailed discussion of my methodology and a series of code tests.

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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin