Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Continuous vs. discrete models for the quantum harmonic oscillator and
  the hydrogen atom   The Kravchuk and Meixner polynomials of discrete variable are introduced for
the discrete models of the harmonic oscillator and hydrogen atom. Starting from
Rodrigues formula we construct raising and lowering operators, commutation and
anticommutation relations. The physical properties of discrete models are
figured out through the equivalence with the continuous models obtained by
limit process.

30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol