def min_approx(x1, x2, x3, y1, y2, y3):
    """
    Get the x-value of the minimum of the parabola through the points (x1,y1), ...
    :param x1: x-coordinate point 1
    :param x2: x-coordinate point 2
    :param x3: x-coordinate point 3
    :param y1: y-coordinate point 1
    :param y2: y-coordinate point 2
    :param y3: y-coordinate point 3
    :return: x-location of the minimum
    """
    #
    div = (2.*(x3*(y1 - y2) + x1*(y2 - y3) + x2*(-y1 + y3)))
    return (x3**2*(y1 - y2) + x1**2*(y2 - y3) + x2**2*(-y1 + y3))/div