covfunc.py 文件源码

def K(self, X, Xstar):
        """
        Computes covariance function values over `X` and `Xstar`.

        Parameters
        ----------
        X: np.ndarray, shape=((n, nfeatures))
            Instances
        Xstar: np.ndarray, shape=((n, nfeatures))
            Instances

        Returns
        -------
        np.ndarray
            Computed covariance matrix.
        """
        r = l2norm_(X, Xstar)
        bessel = kv(self.v, np.sqrt(2 * self.v) * r / self.l)
        f = 2 ** (1 - self.v) / gamma(self.v) * (np.sqrt(2 * self.v) * r / self.l) ** self.v
        res = f * bessel
        res[np.isnan(res)] = 1
        res = self.sigmaf * res + self.sigman * kronDelta(X, Xstar)
        return (res)