Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical Modelling of Optical Trapping   Optical trapping is a widely used technique, with many important applications
in biology and metrology. Complete modelling of trapping requires calculation
of optical forces, primarily a scattering problem, and non-optical forces. The
T-matrix method is used to calculate forces acting on spheroidal and
cylindrical particles.

25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph