Introduction
------------

XFUNC 2.2 is a IBM PC program for DOS.  It is an aid to 
Electronics Engineer who calculates transfer functions using 
symbolic algebra.

The purpose of the program XFUNC is to compute the frequency
domain transfer function of a circuit in symbolic format,
given a circuit description netlist in linear model.  In
addition to this basic feature, the program provides various
extras, which will be discussed in the following sections.

Electronic Engineers, Research Scientists, or Mathematician
will find XFUNC most useful.

Most circuit analysis software such as SPICE on the market
today only give numerical frequency response solution to a
given circuit.  But it is sometimes necessary to find out the
frequency response with respect to various circuit parameters,
and to choose component values to optimize the performance. 
The most direct and proven way to achieve these is to generate
the mathematical transfer function description of the circuit. 
XFUNC saves the Engineer's time and tedious efforts to
generate the symbolic mathematical transfer function.

Another important feature of XFUNC as compared to most other
circuit analysis software is its ability to use state-space
averaging technique to analysis a switching circuit.  Although
SPICE based programs can calculate transient response, they do
not provide frequency response solution to a switching
circuit.  It should be noted that because XFUNC is symbolic
based, it is not designed to handle large circuits.  For most
analog circuit analysis, it is best to break up a large
circuit into small blocks to analyze each block.

In addition to circuit analysis, XFUNC can be used as a simple
tools for symbolic algebra.  Besides addition, multiplication,
etc, it can be used as a symbolic matrix simplifier and
solver.  It also generates plots for the results.

?    User friendly pop-up screen and pull-down menu
      interface.

?    Calculate AC or DC symbolic transfer function.

?    Calculate transfer function in S-domain for Linear
      Circuits or Z-domain for Switching Circuits.

?    Accept resistors, capacitors, inductors, dependent
      sources, ideal opamps, and ideal switches.

?    Component values can be real numbers, symbols, or user
      defined symbolic expressions.

?    Analysis results can be interactively modified.

?    Frequency domain results can be transformed to time
      domain via Inverse Laplace or Z Transform.

?    Transformation between S-domain and Z-domain results can
      be done via Forward or Backward Derivatives (Euler
      Transform), Bilinear, or Impulse Invariant Transforms.

?    Provide Bode, Gain-Phase, Nyquist, Pole-zero, Impulse,
      and Step response plots.  Plot ranges can be set
      manually or automatically.

?    Dynamic array memory allocation avoids overflows while
      minimizing memory requirements.

?    Supplied with its own ASCII editor.

?    Supplied with FASTDUMP utility to plot graphs to Epson,
      IBM Pro, HP Laserjet, or disk files.

Executable Disk - for XFUNC Version 2.2
---------------------------------------

This disk contains the following files:

	i.      README.TXT      - This file.
	ii.     MANUAL.WP5      - The User Manual.
	iii.    XFUNC.BAT       - Start the program.
	iv.     SHELL.EXE       - The executable file.
	v.      ANALYSIS.EXE    - The executable file.
	vi.     OPERATE.EXE     - The executable file.
	vii.    REGISTER.EXE    - The executable file.
	viii.   XFUNC.HLP       - The indexed Help File.
	ix.     XFUNC.CFG       - The Configuration File.
	x.      *.CIR           - A list of Circuit File examples.
	xi.     FASTDUMP.COM    - A screen-dump utility.

To start the program, type XFUNC and press [Enter].  It is recommended that 
you read the User Manual before running the program.  MANUAL.WP5 is the User 
Manual in Word Perfect 5.1 format.  It is setup for an HP LaserJet IIID 
laser printer.  You can also request the over 60 pages of printed User 
Manual for a small fee.  Run the program REGISTER.EXE for details.