def gc_limestone(Vp, A=-0.05508, B=1.01677, C=-1.03049):
    """
    Vs from Vp using Greenberg-Castagna limestone coefficients.

    Vs = A*Vp**2.0 + B*Vp + C
    """

    Vs = A*Vp**2 + Vp*B + C

    return Vs