def kipping_ld(u1,u2):
    """
    Re-parameterize quadratic limb darkening parameters $u_{1}$ and $u_{2}$ according to Kipping (2013)
    
    
    Parameters:
    ----------
    u1: linear limb darkening coefficient.
    
    u2: quadratic limb darkening coefficient.
    
    Returns
    --------
    q1, q2 : Tuple containing the reparametrized limb darkening coefficients
    
    """
    
    q1 = (u1+u2)**2
    q2= u1/(2*(u1+u2))
    
    return round(q1,4), round(q2,4)