Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computing nonlinear force-free fields in spherical geometry   We describe a newly developed code for the extrapolation of nonlinear
force-free coronal magnetic fields in spherical coordinates. The program uses
measured vector magnetograms on the solar photosphere as input and solves the
force-free equations in the solar corona. The method is based on an
optimization principle and the heritage of the newly developed code is a
corresponding method in Cartesian geometry. We test the newly developed code
with the help of a semi-analytic solution and rate the quality of our
reconstruction qualitatively by magnetic field line plots and quantitatively
with a number of comparison metrics. We find that we can reconstruct the
original test field with high accuracy. The method is fast if the computation
is limited to low co-latitudes (say $30^\circ \leq \theta \leq 150^\circ$), but
becomes significantly slower if the polar regions are included.

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The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc