fields.py 文件源码

def d_x2(self, factors=None):
        """Creates a sparse matrix for computing the second derivative with respect to x multiplied
        by factors given for every point. Uses central difference quotient.

        Args:
            factors: Factor for each point to be applied after derivation.

        Returns:
            Sparse matrix the calculate second derivatives of field components.
        """

        # use ones as factors if none are specified
        if factors is None:
            factors = np.array(1).repeat(self.num_points)

        return sp.dia_matrix((np.array([factors, -2*factors, factors]), [-1, 0, 1]),
                             shape=(self.num_points, self.num_points))