Features
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Supports all standard normalizations and phase conventions of the spherical harmonic functions.
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Effortless conversion between real and complex harmonics, between phase conventions, and between 4π normalized, Schmidt semi-normalized, orthonormalized, and unnormalized harmonics.
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Use of both regularly sampled geographic grids and grids appropriate for Gauss-Legendre quadrature.
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Spherical harmonic transforms proven to be fast and accurate to high degrees.
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Supports multiple backends for performing basic mathematical operations, including shtools and the Distinctly Useful Code Collection (DUCC).
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Perform localized multitaper spectral analyses, or expand gridded data in terms of localized Slepian basis functions.
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Supports standard data and file formats, including xarray and netcdf.
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Import research-grade gravity, topography, and magnetic field datasets with a single command.
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Creation of publication quality maps using Cartopy and pygmt.
 
Easy installation
The Python components of SHTOOLS can be installed using the Python package manager pip or conda. Binaries are pre-built for Linux, macOS and Windows architectures, and you need only to execute one of the following commands in a unix terminal:
pip install pyshtools
pip install --upgrade pyshtools  # to upgrade a pre-existing installation
conda install -c conda-forge pyshtools  # Linux and macOS only
conda update -c conda-forge pyshtools  # to upgrade a pre-existing installation
Permissive licensing
SHTOOLS is open source software and is distributed under the 3-clause BSD license.
Reference
Mark A. Wieczorek and Matthias Meschede (2018). SHTools — Tools for working with spherical harmonics, Geochemistry, Geophysics, Geosystems, 19, 2574-2592, doi:10.1029/2018GC007529.
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