Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A Robust Algebraic Domain Decomposition Preconditioner for Sparse Normal
  Equations
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int