Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Hardware based Scale- and Rotation-Invariant Feature Extraction: A
  Retrospective Analysis and Future Directions
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin