def two_pt_parabola(pt1,pt2):
    """
    Given two points, gives us the coefficients for a parabola.
    args:
        pt1: The first point.
        pt2: The second point.
    """
    [x1, y1] = pt1 * 1.0
    [x2, y2] = pt2 * 1.0
    a = (y2-y1)/(x2-x1)**2
    c = y1 + a*x1*x1
    b = -2*a*x1
    return [a,b,c]