Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical Methods for the 3-dimensional 2-body Problem in the
  Action-at-a-Distance Electrodynamics   We develop two numerical methods to solve the differential equations with
deviating arguments for the motion of two charges in the action-at-a-distance
electrodynamics. Our first method uses St\"urmer's extrapolation formula and
assumes that a step of integration can be taken as a step of light ladder,
which limits its use to shallow energies. The second method is an improvement
of pre-existing iterative schemes, designed for stronger convergence and can be
used at high-energies.

34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg