ABSTRACT
The program is divided into two parts: the invariant part and the adaptation part. The invariant part embodies the general numerical procedure. The adaptation part provides the framework for the user-supplied information for the specific problem to be solved. It indicates all the subprograms and their interrelations. Only the important "calls" are shown; double arrows imply that multiple calls are made to the particular subroutine. The MAIN subprogram controls the sequence of important operations by calling a number of subroutines. The subprogram TOOLS is actually not an essential part of the computer program. It is, however, provided as an aid to someone in designing the adaptation part of the program. The subprogram ADAPT contains four member subroutines; they are: GRID, BEGIN, OUTPUT, and PHI. Of these, GRID and BEGIN are called only once and provide grid-related geometrical information and initial values respectively.
