Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-dimensional analytical discrete-ordinates method for the radiative
  transport equation   The radiative transport equation in a three-dimensional infinite medium is
considered. The coefficients of the radiative transport equation are assumed to
be constant. For a pencil beam, we extend the analytical discrete-ordinates
method to three dimensions by rotating reference frames. Obtained results are
compared to Monte Carlo simulation.

27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph