Formula Graphing Applets
See Java class documentation.
This demonstrates one program from the package, "graphing",
of Java classes I am developing to use for graphing
mathematical functions in educational demonstrations.
The applet on this page lets you investigate how the slope of a secant line on a curve
(the straigh line joining two points on the curve) varies as the points on the curve
move, and, in particular explore its behavior quantitatively as the two points move very
close together. In the latter case the slope of the secant line approxiamtes the value
of the derivative that that point.
Instructions:

Adding Functions

Press "Add Function" button and type in a formula to be graphed in standard mathematical notation
(eg "e^(x/10)sin(x)"). The only variable the formula can use is x.
You can add as many functions as you like, and "Delete Function" deletes the last one you
entered.

Rescaling

This brings up a panel which you can use to edit the scale of the graph. The x
variable runs between xMin and xMax, and the y values run between yMin
and yMax. Use xScale and yScale to
set the spacing of tick marks on the axes. If xScale or yScale is zero, the
graph will have no tickmarks on that axis.

Zooming

You can change the scale of your picture quickly with "Zoom In", "Zoom Out" and "Zoom to Box".
The first two zoom in or out around the center of the graph. If you click and drag on the graphing
window, you can draw out a box, and Zoom To Box will zoom in to make that box fill the whole
window.
Secant Lines
Click on the curve to mark a point on the curve. Click on a second
point on the curve and another point is also selected, and you
see the straight line (secant line) joining them. As you drag either one,
the line and its slope change. If you select the ceheckbox to show the slope,
the slope of the line is displayed on the screen as the nodes move.
If you want to delete one or both nodes, draw out a box on the screen (as though
you were going to zoom in) that encloses the nodes you want to delete, and then
press the "backspace" key.
Please play with the program here, and see what it can do.It's still under
development; so go ahead and try to break it, and let me know if you can!
If you like my program and you want to use it in your pages, just include the tag
in your web pages and you'll get what you see here!
If you have suggestions for changes, developments, or extensions of this program please mail me.
Please mail me with bug reports too!