Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Antenna Array Signal Processing for Quaternion-Valued Wireless
  Communication Systems
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga