SHTOOLS/pysthools is a Fortran-95/Python library that can be used to perform spherical harmonic transforms and reconstructions, rotations of data expressed in spherical harmonics, and multitaper spectral analyses on the sphere.

FEATURES

• A wide range of supported spherical harmonic functions:

  • real and complex,
  • all standard normalizations (Geodesy 4π, Schmidt semi-normalized, orthonormalized, unnormalized),
  • Condon-Shortley phase factor of (-1)^m.

• Selected applications and routines:

  • global spectral analysis, spherical harmonic rotations, Wigner 3j symbols,
  • localized multitaper spectral analyses, optimal window generation, spherical harmonic coupling matrices,
  • standard gravity and magnetic field calculations, computation of the geoid, finite-amplitude potential from topography.

• Clean implementation of the spherical harmonic transforms:

  • exact quadrature rules using the sampling theorem of Driscoll and Healy (1994) or Gauss-Legendre quadrature,
  • accurate and fast to approximately degree 2800 (spatial resolution higher than 4 arc minutes),
  • Fortran 95 routines are OpenMP compatible and OpenMP thread-safe.

INSTALLATION

pyshtools for Python

Binary install for linux/macOS/windows:

pip install pyshtools

Build from source:

pip install pyshtools --no-binary pyshtools

pyshtools for Anaconda Python

Install fftw3 with fortran bindings and then install pyshtools using pip:

conda install -c eumetsat fftw3
pip install pyshtools

pyshtools for Python (developer install)

Linux requirements:

sudo apt-get install libblas-dev liblapack-dev g++ gfortran libfftw3-dev tcsh

macOS requirements:

brew install fftw --with-fortran

To install the develop branch use:

pip install git+https://github.com/SHTOOLS/SHTOOLS@develop

Alternatively, clone the shtools repo

git clone https://github.com/SHTOOLS/SHTOOLS.git

and then execute one of the following commands in the shtools directory:

pip install .  # installs into the active python environment lib folder
pip install -v -e .  # installs into the SHTOOLS/pyshtools folder and links to the active python environment

Fortran Library

Clone the shtools repo, and then execute one of the following commands in the shtools directory:

make fortran
make fortran-mp  # OpenMP Fortran routines

Or use the brew package manager (macOS):

brew tap shtools/shtools
brew install shtools
brew install shtools --with-openmp # to install shtools with the OpenMP components.

More installation instructions and options can be found in the web documentation and GitHub wiki.

HOW TO USE

SHTOOLS can be invoked from Fortran 95, Python 2 or Python 3. The base SHTOOLS software is written in Fortran 95, and the Python library allows simple access to all fortran-compiled routines and offers helper routines as well as simple interfaces.

To get started, check out the following Python tutorial notebooks:

• Introduction 1: Grids and Spherical Harmonic Coefficients
• Introduction 2: Localization Windows and Spectral Analysis

ACKNOWLEDGMENTS

SHTOOLS is open source (revised BSD license) and makes use of the freely available Fourier transform package FFTW and the linear algebra packages LAPACK and BLAS.

CITATION

Mark A. Wieczorek and Matthias Meschede (2018). SHTools --- Tools for working with spherical harmonics, Geochemistry, Geophysics, Geosystems, doi:10.1029/2018GC007529.

M. A. Wieczorek, M. Meschede, E. Sales de Andrade, I. Oshchepkov, B. Xu, and A. Walker (2018). SHTOOLS, Zenodo, doi:10.5281/zenodo.592762.