def ppf(q, df, loc=0.0, scale=1.0, gamma = 1.0):
        """
        PPF function for Skew t distribution
        """
        result = np.zeros(q.shape[0])
        probzero = Skewt.cdf(x=np.zeros(1),loc=np.zeros(1),df=df,gamma=gamma)
        result[q<probzero] = 1.0/gamma*ss.t.ppf(((np.power(gamma,2) + 1.0) * q[q<probzero])/2.0,df)
        result[q>=probzero] = gamma*ss.t.ppf((1.0 + 1.0/np.power(gamma,2))/2.0*(q[q >= probzero] - probzero) + 0.5, df)
        return result