You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: SO3DeLaValleePoussinKernel.m
    path of file: ./repos/mtex/SO3Fun/SO3KernelFunctions
    
    the code of the file until where you have to start completion: classdef SO3DeLaValleePoussinKernel < SO3Kernel
% The rotational de la Vallee Poussin kernel is define
    
function has reduced to half its peak value  
%  bandwidth - harmonic degree
%
% See also
% SO3Kernel

properties
  kappa = 90;
  C = [];
end
      
methods
    
  function psi = SO3DeLaValleePoussinKernel(varargin)
    
    % extract parameter and halfwidth
    if check_option(varargin,'halfwidth')
      hw = get_option(varargin,'halfwidth');
      psi.kappa = 0.5 * log(0.5) / log(cos(hw/2));
    elseif nargin > 0
      psi.kappa = varargin{1};
    end