3D Parametric Equation Plotter

3D Parametric Equation Plotter
------------------------------
REQUIREMENTS: VMD Version 1.8 or greater
DESCRIPTION:
	The draw_surface proc generates sample points on a parametric surface
 defined by three two-variable functions 'f', 'g', and 'h'.
 Each of the functions accepts two parameters 'u' and 'v'. 
 The the draw_surface requires three parameters which are the 
	the procedure names which implement the functions 'f', 'g', and 'h'.
 Limits of evaluation and interval size can be set within the body 
 of the draw_surface procedure.
	To start you off, sample functions 'f', 'g', and 'h' have 
 been provided.
	
PROCEDURES:
	f - function for the x-component of the parametric surface to plot
	g - function for the y-component of the parametric surface to plot 
	h - function for the z-component of the parametric surface to plot 
	draw_surface - calculates points of f, g, and h, and plots them
EXAMPLE USAGE:
	To plot the parametric surface, which is a function of two variables:
 source 3dparplot.tcl
 draw_surface f g h
EXAMPLE OUTPUT:
	
DOWNLOAD FILE:
	3dparplot.tcl
AUTHOR:
	John Stone (johns@ks.uiuc.edu)