**MATLAB routine diskmethod.m**

GENERATE SURFACES of REVOLUTION by rotating y = f(x) about the x-axis.

This is to be used as a visual aid for showing the notions behind the

generation of surfaces of revolution and leading to the calculus integral

expression for the volume of such surfaces.

This is an interactive program that takes as input

expression for y = f(x),

domain interval [a,b],

and the number slices to be taken across the domain. (MAX 10 slices.)

With this information the curve is sketched in the xy-plane and radii

shown for the slices to generated. A slice near the middle of the region

is then colored to show a strip of area. Next we show the cross sections

of the slices in three dimensions and the cylinder disk generated by the

colored strip. This is followed by the generation of cylindrical disks

corresponding to each of the slices. The sum of the volumes of these

cylindrical disks would yield an approximation the volume of the surface

of revolution. Finally the entire surface of revolution is displayed.

Once this surface has been generated, it can be rotated using the

MATLAB tools appearing in the toolbar.

A user must click in the input boxes and then type the requisite data.

No check for validity of the data entered is made. If there is an error

MATLAB will generate a message on the text screen when the data is processed.

If you click in an input box and then press enter default data will appear.

The default values are f(x)= x^{2} over [0,1] with 10 slices.

Throughout this demonstration utility buttons for HELP, RESTARTing,

and QUITing are available.

The routine does no volume computations, rather can be used to motivate

the calculus formula for the volume.

AUXILIARY ROUTINES: addaxes, addaxes3, cylind1 by D.R.Hill

By: David R. Hill

Math Dept

Temple University,

Philadelphia, Pa. 19122

Email: dhill001@temple.edu

and

Lila F. Roberts

Department of Mathematics

Georgia College & State University

Milledgeville, GA 31061

Email: lila.roberts@gcsu.edu

Constructed 3/1/2002 Last updated 5/19/2006 DRH