# Get a new `Point3d[Float]` at an offset of `x, y, z` from `self`
	#
	# ~~~
	# var origin = new Point3d[Float](1.0, 1.0, 1.0)
	# assert origin.offset(1.0, 2.0, 3.0).to_s == "(2.0, 3.0, 4.0)"
	# ~~~
	fun offset(x, y, z: Numeric): Point3d[Float]
	do return new Point3d[Float](self.x.to_f+x.to_f,
	                             self.y.to_f+y.to_f,
	                             self.z.to_f+z.to_f)