def _kurtosis(self, x, z, d=0):
        """ returns the kurtosis parameter for direction d, d=0 is rho, d=1 is z """
        val = self._poly(z, self._kurtosis_coeffs(d))
        return (np.tanh(val)+1)/12.*(3 - 6*x**2 + x**4)
def _kurtosis(self, x, z, d=0):
        """ returns the kurtosis parameter for direction d, d=0 is rho, d=1 is z """
        val = self._poly(z, self._kurtosis_coeffs(d))
        return (np.tanh(val)+1)/12.*(3 - 6*x**2 + x**4)
def _kurtosis ( self , x , z , d = 0 ) : val = self . _poly ( z , self . _kurtosis_coeffs ( d ) ) return ( np . tanh ( val ) + 1 ) / 12. * ( 3 - 6 * x ** 2 + x ** 4 )
returns the kurtosis parameter for direction d, d=0 is rho, d=1 is z
returns the kurtosis parameter for direction d d = 0 is rho d = 1 is z