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F r e e g r a p h
P a g e
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@ Hunter-Lovell.org
[ Updated: September 2, 2003 ]
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What is
Freegraph?
Overview:
Freegraph is a Java applet which will graph equations of the
form y=???, where ??? is an expression with the variable X.
(For instance, y=5x+3/x)
There is also an equation solver
and expression parsing applet to go along with the grapher.
Features: Features of Freegraph include zooming
with the mouse, graphing multiple equations, and free-form
expression parsing without the need for explicit
multiplication signs.
For Developers: Freegraph
is a package of Java classes for parsing and evaluating
expressions. Freegraph is Java 1.1 compatible for use in
applets without the Java plugin. Freegraph also includes
an Equation Solver, Expression Parser, and a Graphing
Applet. Source code is available and free for any use
(including commercial). We will officially provide an Apache
or BSD style license soon.
Improvements, extensions, and bug fixes are encouraged and
welcome. Please email them.
The project is helped by having more applets and applications
which use the library. If you build an applet or application,
it would be helpful to provide it so that it can be posted
on this web page.
Click here for source.
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Complete Freegraph Source Code and Documentation
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Freegraph
Grapher
Press the "Start
Grapher" button:
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Instructions
for Grapher:
To Start, press the Start Grapher button.
To Graph, enter a function and press the [Add]
button. (Enter the function just to the right of the Add
button.)
To zoom in, draw a box on the graph area with the
mouse. (Left click and drag.)
To zoom out or reset axis, use the buttons at the
top or invoke a popup-menu on the graph area.
Example Functions:
5x+3
5/x
x^2sqrt(x)5sinx(-5xsin(4-x))/(3-x)
To remove a function from the list, select it and
press [Remove].
To clear all functions, press [Clear]
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Expression
Parser
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Instructions
for Expression Parser:
Purpose:
The
expression parser will convert an infix expression into a
RPN (a.k.a. postfix) expression stack. For more information on RPN, click
here.
To use the applet:
Enter a function
into the text field.
Press the "Convert" button and the
RPN stack will be displayed as a list.
The algorithm used is from: Tanenbaum, Andrew S. 1990. Structured Computer Organization, 3rd ed.,
New Jersey: Prentice Hall. (pp. 268-272)
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Equation
Solver
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Instructions
for Equation Solver:
Type in an equation
and press solve, press ... for advanced solving options.
The Applet uses Bisection and Newton's equation solving
techniques.
The advanced options allow you to set the
range for the bisection technique, and the starting X value
for Newton's technique. The repeat check boxes cause the
techniques to be re-tried with different parameters to search
for a solution.
Links with more information on:
Bisection and Newton's Method
Examples:
5x=25
3(x+2)=18
21/x=7
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Solver
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