def parameter_of_point_on_line(a, b, point):
    """
    Get the parameter of a point on a line. For this function to give a
    correct result it is important that the provided point already lies on the
    line. The :func:`closest_point_on_line` can be used to get that point on the
    line.

    :param OpenMaya.MVector a:
    :param OpenMaya.MVector b:
    :param OpenMaya.MVector point:
    :return: Parameter of the point on the line
    :rtype: float
    """
    # get vectors
    ap = point - a
    ab = b - a

    # get parameter
    parameter = ap.length() / ab.length()
    return parameter