Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact boundary conditions in numerical relativity using multiple grids:
  scalar field tests   Cauchy-Characteristic Matching (CCM), the combination of a central 3+1 Cauchy
code with an exterior characteristic code connected across a time-like
interface, is a promising technique for the generation and extraction of
gravitational waves. While it provides a tool for the exact specification of
boundary conditions for the Cauchy evolution, it also allows to follow
gravitational radiation all the way to infinity, where it is unambiguously
defined.
  We present a new fourth order accurate finite difference CCM scheme for a
first order reduction of the wave equation around a Schwarzschild black hole in
axisymmetry. The matching at the interface between the Cauchy and the
characteristic regions is done by transfering appropriate characteristic/null
variables. Numerical experiments indicate that the algorithm is fourth order
convergent. As an application we reproduce the expected late-time tail decay
for the scalar field.

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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
3
The categories of this paper are: physics
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The categories of this paper are: alg-geom
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci