Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Hierarchical Butterfly LU Preconditioner for Two-Dimensional
  Electromagnetic Scattering Problems Involving Open Surfaces   This paper introduces a hierarchical interpolative decomposition butterfly-LU
factorization (H-IDBF-LU) preconditioner for solving two-dimensional
electric-field integral equations (EFIEs) in electromagnetic scattering
problems of perfect electrically conducting objects with open surfaces.
H-IDBF-LU leverages the interpolative decomposition butterfly factorization
(IDBF) to compress dense blocks of the discretized EFIE operator to expedite
its application; this compressed operator also serves as an approximate LU
factorization of the EFIE operator leading to an efficient preconditioner in
iterative solvers. Both the memory requirement and computational cost of the
H-IDBF-LU solver scale as $O(N\log^2 N)$ in one iteration; the total number of
iterations required for a reasonably good accuracy scales as $O(1)$ to
$O(\log^2N)$ in all of our numerical tests. The efficacy and accuracy of the
proposed preconditioned iterative solver are demonstrated via its application
to a broad range of scatterers involving up to $100$ million unknowns.

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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
9
The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex
27
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: mtrl-th