Introduction

GrafLab (GRAvity Field LABoratory) is a MATLAB-based routine to compute functionals of the geopotential up to high degrees (tens of thousands and beyond).

Features:

• Evaluates 38 functionals of the geopotential (e.g., the geoid, height anomaly, gravity anomalies/disturbances, deflections of the vertical, gravitational tensor).

• Evaluates the commission error of 26 functionals using a full variance-covariance matrix of spherical harmonic coefficients.

• Supports efficient FFT-based synthesis at grids and point-by-point synthesis at scattered points.

• Reads models in the gfc format defined by ICGEM.

• Works with evaluation points defined by spherical as well as ellipsoidal coordinates.

• Plots output data on a map.

Users can interact with GrafLab either through a GUI (the figure below) or from the command line.

For a few simple applications of GrafLab, you may visit https://www.blazejbucha.com/#GrafLab.

Documentation

If you want just a brief introduction to GrafLab, see docs/user-manual.md.

Detailed GrafLab cookbook is available at https://github.com/blazej-bucha/graflab-cookbook.

To go through the equations implemented in GrafLab, see docs/Definition_of_functionals_of_the_geopotential_used_in_GrafLab_software.pdf.

Contributing

Contributions of any kind are welcome!

Contact

Feel free to contact the author, Blazej Bucha, at blazej.bucha@stuba.sk.

Citing

If you use GrafLab in your work, please consider citing our paper on GrafLab.

• Bucha, B., Janák, J., 2013. A MATLAB-based graphical user interface program for computing functionals of the geopotential up to ultra-high degrees and orders. Computers & Geosciences 56, 186-196, https://doi.org/10.1016/j.cageo.2013.03.012

Other related projects

• CHarm: C library for spherical harmonic transforms up to high degrees (tens of thousands and beyond). Supports OpenMP parallelization for shared memory architectures and vectorized CPU instructions (AVX, AVX2, AVX-512).

• isGrafLab (Irregular Surface GRAvity Field LABoratory): A modified version of GrafLab to perform accurate and fast synthesis of gravity field quantities at dense grids residing on irregular surfaces such as the Earth's surface.

Disclaimer

GrafLab is an old project that breaks almost all of the best practices in terms of coding and documenting standards. Nonetheless, the package seems to work correctly, it has been thoroughly tested and the computation speed is reasonable (as far as it is possible in MATLAB). Hoping it might still be useful to others, GrafLab remains being publicly available.