def cubicPolyCoeffs(a, b, c, d):
	"""Converts the four control points of a cubic Bezier curve into the degree-3 polynomial form.
	Returns the coefficient of the monomials of degree 1, 2 and 3."""
	return 3.0*(b-a), 3.0*(c - 2.0*b + a), d + 3.0*(b - c) - a