Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solidfmm: A highly optimised library of operations on the solid
  harmonics for use in fast multipole methods   We present solidfmm, a highly optimised C++ library for the solid harmonics
as they are needed in fast multipole methods. The library provides efficient,
vectorised implementations of the translation operations M2M, M2L, and L2L, and
is available as free software. While asymptotically of complexity $O(P^3)$, for
all practically relevant expansion orders, the translation operators display an
empirical complexity of $O(P^2)$, outperforming the na\"ive implementation by
orders of magnitude.

2
The categories of this paper are: math
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc