ECAP II-a new electronic circuit analysis program

ECAP II is a nonlinear d.c. and transient circuit analysis program capable of handling circuits larger than 1000 branches. It uses a free-format problem-oriented input language for describing the circuit parameters and topology. The program includes a nested model feature that permits the user to store in a model library circuit descriptions of devices, subcircuits, etc., for subsequent recall and insertion into larger circuits. Nonlinearities can be specified by means of tables, certain built-in functions such as the diode equation, and Fortran subroutines. All circuit elements can be made to depend on any current or voltage, on other circuit parameters, or on time itself. The user may specify which variables are to be printed out or plotted and what type of analysis is to be carried out. Diagnostics are provided to pinpoint errors in the input format and/or inconsistencies in the circuit description. A number of new mathematical and programming techniques are incorporated in the program, including sparse matrix storage and computation, dynamic storage allocation, and variable order implicit integration.