Gravity computation using spherical harmonics

The software target is the development of a user interface to run an existing tool (written in ANSI-C) for the evaluation of the gravity signal from a set of spherical harmonic coefficients, namely, from a global gravity model allowing for the computation all over the world and at any height above the Earth surface. The existing tool should be adapted to work in quadruple precision to have a suitable numerical accuracy. A typical input is a global model like those provided by the ICGEM service (https://icgem.gfz-potsdam.de), while a typical output is the geoid undulations or the gravity anomalies over a certain region. Some filtering and change of coordinates may be also required. The software interface has to be developed in Python.