Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An R-matrix package for coupled-channel problems in nuclear physics   We present an $R$-matrix Fortran package to solve coupled-channel problems in
nuclear physics. The basis functions are chosen as Lagrange functions, which
permits simple calculations of the matrix elements. The main input are the
coupling potentials at some nucleus-nucleus distances, specified by the
program. The program provides the collision matrix and, optionally, the
associated wave function. The present method deals with open and closed
channels simultaneously, without numerical instability associated with closed
channels. It can also solve coupled-channel problems for non-local potentials.
Long-range potentials can be treated with propagation techniques, which
significantly speed up the calculations. We first present an overview of the
$R$-matrix theory, and of the Lagrange-mesh method. A description of the
package and its installation on a UNIX machine is then provided. Finally, five
typical examples are discussed.

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The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: cs
3
The categories of this paper are: physics
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The categories of this paper are: stat
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg