This file accompanies the program xFunctions 2.3 for Macintosh
computers.  This program is protected by copyright, but is
distributed without charge.  It can be freely distributed.
This is meant to explicitely include anonymous FTP sites,
BBS's (provided no charge is made above regular membership
fees), and inexpensive CD-ROM shareware collections.

The version distributed with this README file will work on any Macintosh.
I have another version that requires a Macintosh with an FPU (floating
point unit).  As of February 1995, both versions of the program can
be obtained via FPT or Gopher to math.hws.edu.  I will also be happy to
send you a copy of the FPU version, by E-mail in BinHex format or on a
floppy disk.  Comments, inquiries and bug reports are welcome.

XFunctions is a general-purpose program for playing with
mathematical functions.  It is not meant for use in scientific
analysis or for making presentation-type graphs and charts.  It was
written primarily to help students learn mathematics.  A major goal
in writing the program was to make it as easy as possible to use,
so that students can concentrate on learning about mathematics,
rather than learning about computers.  It is also fun just to play
with (at least if you are mathematically inclined).

I wrote the program xFunctions primarily for use in Calculus and
pre-Calculus courses.  In courses that I teach, I have used it in a
lab setting (where the students have immediate access to help), in
combination with problem sets that encourage the students to
explore concepts and then to write about what they have learned.

Interesting features include:  New functions can be input as either
single formulas, split functions, graphs, or tables.  A knife tool
can be used to cut out a rectangle on a graph for enlargement. 
Seven special "utility" operations include:  graphing several
graphs on one set of axes; animation of a family of functions of
the form f(x,k); graphing of derivatives and tangent lines; Riemann
sums, with graphical display; graphs of parametrically defined
curves; integral curves of vector fields; and three-dimensional
plots of functions z = f(x,y);  A limited printing facility is
provided.  Files can be saved containing utility examples and
functions that you input.  (A sample file of examples should
accompany this program.)  An "Info" menu is available when the
program is run to give full information on the program and the
seven utilities.

I am no longer actively working on this program, and have no
plans to update it extensively.  Version 2.3 includes a few minor
bug fixes and a few new features: "Zoom In" and "Zoom Back" commands
in the Display Menu; a Display "As Table with Cluster Point" command
in the Display Menu; and a "Clone Function" command in the Function
Menu.  (Many of the changes were suggested by John Harris of the
University of Otago in New Zealand.)


David Eck
Department of Mathematics and Computer Science
Hobart and William Smith Colleges
Geneva, NY   14456
E-mail: eck@hws.edu
WWW:    http://hws3.hws.edu:9000/eck/index.html

February 27, 1995