Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere
  Program. II: Wavelength Parallelization   We describe an important addition to the parallel implementation of our
generalized NLTE stellar atmosphere and radiative transfer computer program
PHOENIX. In a previous paper in this series we described data and task parallel
algorithms we have developed for radiative transfer, spectral line opacity, and
NLTE opacity and rate calculations. These algorithms divided the work spatially
or by spectral lines, that is distributing the radial zones, individual
spectral lines, or characteristic rays among different processors and employ,
in addition task parallelism for logically independent functions (such as
atomic and molecular line opacities). For finite, monotonic velocity fields,
the radiative transfer equation is an initial value problem in wavelength, and
hence each wavelength point depends upon the previous one. However, for
sophisticated NLTE models of both static and moving atmospheres needed to
accurately describe, e.g., novae and supernovae, the number of wavelength
points is very large (200,000--300,000) and hence parallelization over
wavelength can lead both to considerable speedup in calculation time and the
ability to make use of the aggregate memory available on massively parallel
supercomputers. Here, we describe an implementation of a pipelined design for
the wavelength parallelization of PHOENIX, where the necessary data from the
processor working on a previous wavelength point is sent to the processor
working on the succeeding wavelength point as soon as it is known. Our
implementation uses a MIMD design based on a relatively small number of
standard MPI library calls and is fully portable between serial and parallel
computers.

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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: stat
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol