EARTH is the central program of PHOENICS. The parts of its source coding which are directly accessible to the user are:-
EARTH contains software which represents the relevant laws of physics applied to elements of material distributed in space and time.
EARTH reads the EARDAT file provided by SATELLITE and executes the corresponding computations; it then produces a human-readable output file called RESULT, and also a second file, usuall called PHI, which can be read by the display modules PHOTON and AUTOPLOT, by the file-handling utility PINTO, or by EARTH itself when a new run is started.
The relationships of EARTH to SATELLITE and the other PHOENICS components are illustrated by the screen display of the PHOENICS Commander.
EARTH possesses user-accessible FORTRAN subroutines, namely the files MAIN and GROUND. The former is used primarily for changing the values of parameter which appear in DIMENSION statements; but GROUND, which stands for "ground-station", can be used for a variety of data-setting and feature-adding purposes.
See also PHENC entries: SATELLITE, and GROUND