Compute analytical geometrical factors.

        TODO: use real electrode positions from self.grid

def compute_K_factors(self, spacing=None, configs=None, numerical=False,
                          elem_file=None, elec_file=None):
        """Compute analytical geometrical factors.

        TODO: use real electrode positions from self.grid
        """
        if configs is None:
            use_configs = self.configs
        else:
            use_configs = configs

        if numerical:
            settings = {
                'elem': elem_file,
                'elec': elec_file,
                'rho': 100,
            }
            K = edfK.compute_K_numerical(use_configs, settings)
        else:
            K = edfK.compute_K_analytical(use_configs, spacing=spacing)
        return K