Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Equivalence of the Digital Waveguide and Finite Difference Time
  Domain Schemes   It is known that the digital waveguide (DW) method for solving the wave
equation numerically on a grid can be manipulated into the form of the standard
finite-difference time-domain (FDTD) method (also known as the ``leapfrog''
recursion). This paper derives a simple rule for going in the other direction,
that is, converting the state variables of the FDTD recursion to corresponding
wave variables in a DW simulation. Since boundary conditions and initial values
are more intuitively transparent in the DW formulation, the simple means of
converting back and forth can be useful in initializing and constructing
boundaries for FDTD simulations.

18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex