Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Direct Method for Calculating the Inverse Radon Transform and Its
  Applications
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat