# How to revolve a function f(x) around the x-axis in MATlab or Mathematica

1. Sep 21, 2004

### VinnyCee

How does one revolve a function f(x) around the x-axis in MATlab or Mathematica?

How would one go about making a visual representation of a function revolved around the x-axis to make a "solid of revolution" in a program like MATlab or Mathematica? For example, a function y = sin(x) can be rotated around the x-axis from x = -3.14 to 3.14, creating a 3D object that has a volume given by the definite integral of pi*sin(x)^2 dx from -3.14 to 3.14. Please help, been trying this for days!

Last edited: Sep 21, 2004
2. Sep 22, 2004

### plover

For Mathematica: have you looked at the GraphicsSurfaceOfRevolution package?

3. Sep 23, 2004

### enigma

Staff Emeritus
You need to build a line in one plane which you're going to revolve, and then run a 'for' loop adding new points as you rotate the original line about the axis using a 3x3 rotation matrix.

Then look up the 'mesh' command for syntax getting the points placed in MATLAB.

Is that enough to get you started?