The following command just turns off an annoying message. Don't worry about it. 

[Graphics:Images/index_gr_1.gif]

Assume that the constants [Graphics:Images/index_gr_2.gif] below are always positive.

Ellipsoids
Paraboloid
Cone
Hyperboloid of one sheet
Hyperboloid of two sheets
Hyperbolic paraboloid (saddle) #1

Converted by Mathematica      October 10, 2001