# Quadratic Bézier interpolation between `a` and `b` with an `handle` using `self` as weight
	#
	# ~~~
	# assert  0.00.qerp(0.0, 32.0, 128.0) == 0.0
	# assert  0.25.qerp(0.0, 32.0, 128.0) == 20.0
	# assert  0.50.qerp(0.0, 32.0, 128.0) == 48.0
	# assert  0.75.qerp(0.0, 32.0, 128.0) == 84.0
	# assert  1.00.qerp(0.0, 32.0, 128.0) == 128.0
	# ~~~
	fun qerp(a, handle, b: Float): Float do
		var p = self
		var i = 1.0 - p
		var r =     i*i * a +
			2.0*i*p * handle +
			    p*p * b
		return r
	end