Routine Name:	plane

Description:	Generates 3-D coordinates for a plane with specified
		dimensions and characteristics.

Usage:		plane filename x y dx dy [-center cx cy] [-jitter jx jy]
			[-normal] [-ellipse] [-hexagonal]

		filename	name for file into which to put generated
				coordinates

		x		x dimension of rectangular area; if -e option
				selected, x axis of ellipsoid area

		y		y dimension of rectangular area; if -e option
				selected, y axis of ellipsoid area

		dx		spacing in x dimension between points

		dy		spacing in y dimension between points

		-center		flag specifying that center of plane should be
				set at coordinates (cx,cy) (default: (0,0))

		cx		x coordinate of center of plane (default: 0)

		cy		y coordinate of center of plane (default: 0)

		-jitter		flag specifying that linearly random jitter
				should be added to offset coordinates from a
				perfect array (jitter in x dimension will vary
				in range -jx*dx < jitter < jx*dx; jitter in y
				dimension will vary in range
				-jy*dy < jitter < jy*dy)

		jx		jitter in x dimension (as fraction of dx)
				(default: 0)

		jy		jitter in y dimension (as fraction of dy)
				(default: 0)

		-normal		flag specifying that an additional set of 3
				coordinates is generated per line, to define
				the normal to the surface (this format is
				compatible with that read by the cellsheet
				routine)

		-ellipse	flag specifying that generated coordinates
				should be restricted to lie in an ellipse with
				major axes specified by x,y

		-hexagonal	(not yet implemented) flag specifying that
				generated coordinates should lie in a
				hexagonal (rather than rectangular) array

Example:	plane planepoints 400e-6 400e-6 100e-6 100e-6 -normal

Notes:		All of the cells in the plane have an initial z coordinate of
		0.0.  (See position for how to change this).

See also:	egg, cellsheet

