The acronym RNPL stands for Rapid Numerical Prototyping Language. It is a language for expressing time-dependent systems of partial differential equations and the information necessary for solving them using finite-difference techniques. It has advantages over traditional programming languages such as C and FORTRAN because it only requires the user to enter the essential structure of the program while it fills in the details.
RNPL can produce complete working programs, or a ``skeleton'' that the user can complete. The programs include facilities for reading parameters from a file, interactive control over output times and functions, memory management, and state dumping for calculation interruption and restart. Throughout this manual, program examples will be given in Courier , while the rest of the text will be in Times.