Plotting Applet
The purpose
of this applet is to plot functions. It can plot up to 10 different functions
at the same time. It can also be used to solve equations numerically.
Its functions as follows:
 The Viewing
Window Parameters area is used to set the area of the graph the
user wishes to see. Use it as follows:
 Specify the
desired values for XMin, XMax, YMin, YMax. The applet will do basic
error checking. If a entry other than a number is typed in, an error
will be displayed, and the focus will remain in the field which
caused the error.
 When Use
yrange is checked, the supplied values for the yrange will
be used Otherwise, the applet will find YMin and YMax from the supplied
functions.
 Any change
in this area will take effect only after the Plot button
is pressed.
 The Function
Information area is where the functions to be plotted are entered.
Use this area as follows:
 To enter a
new function, always press the New Function button. Then,
enter the expression defining the function. The syntax is similar
to the syntax used in the Java Math Engine. For example, to defines
the sine function, you would type in sin(x). Make sure you use x
for the variable in your definition.
 A maximum of
10 functions can be defined at the same time.
 Checking Active
means the function will show on the graph. Unselecting it means
the function will not show.
 Use the + and
 buttons to scroll through the list of defined functions.
 Each defined
function has a different color assigned to it. The selection is
automatic.
 When a function
is defined, it is automatically assigned a name of the form fi where
i is a number which starts at 1 and is incremented every time a
new function is defined. The name a function will be saved under
appears to the left of the field where it is defined.
 Once a function
is defined, its name can be used in the definition of other functions.
For example, if two functions have been defined, the definition
of function 3 could be f1(x)+x*f2(x) Note that we use f1(x) and
not just f1.
 The functions
defined will plot only after Plot has been pressed.
 Del Function
will delete the function currently showing. When deleting a function,
make sure that it is not used in the definition of another function.
An error would occur in this case. For example, if f2(x) = x + f1(x)
and f1 is deleted, then the definition of f2 contains an unknown
symbol, f1.
 The Zoom and
Trace area is where zooming and tracing take place. Use this area
as follows:
 To zoom in,
picture in your mind the rectangular region you would like to zoom
in. Left click on one of the corners of this imaginary region. While
holding the mouse button down, move it to the opposite corner, then
release it. As you move the mouse, a rectangle will be drawn to
help you visualize the region. Once the mouse button is released,
the graph will redraw, XMin, XMax, YMin, YMax will be updated.
 To go back
to the original view (XMin = 10, XMax = 10, YMin = 10, YMax =
10), press Reset Zoom.
 To trace, simply
single left click in the graph area. A point will be generated by
taking the xcoordinate of the point where you clicked and the ycoordinate
on the function currently showing.
 To move the
point, use the Right or Left buttons. The point will
move on the function currently showing. By selecting a different
function, you can select which function you want your point to follow.
 The coordinates
of the point will be displayed under X: and Y:.
 The Control
Buttons area contains buttons which have a global effect for the
applet.
 The Clear
All button erases all the function definitions.
 The Plot
button is used to update the plot area after changes in the other
areas have been made.
 The Messages
area is where the applet communicates with the user. Error messages
as well as user information is displayed there. Errors are displayed
in red, while information is displayed in black.

