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: exp.m
    path of file: ./repos/mtex/geometry/@Miller
    
    the code of the file until where you have to start completion: function ori = exp(m,ori_ref,varargin)
% misorientation vector to misorientation
%
% Description
% 
% Syntax
%
%   mori = exp(m)        % misorientation
%
%   ori = exp(m,ori_ref) % orientation update
%
% Input
%  m - @Miller misorientation vector in crystal coordinates
%  ori_ref - @orientation
%

    
function ori = exp(m,ori_ref,varargin)
% misorientation vector to misorientation
%
% Description
% 
% Syntax
%
%   mori = exp(m)        % misorientation
%
%   ori = exp(m,ori_ref) % orientation update
%
% Input
%  m - @Miller misorientation vector in crystal coordinates
%  ori_ref - @orientation
%
% Output
%  ori - @orientation
%
% See also
% Miller/exp orientation/log

rot = exp@vector3d(m);

ori = orientation(rot,m.CS,m.CS);

if nargin >= 2
  if check_option(varargin,'left')
    ori =  ori * ori_ref;
  else
    ori =  ori_ref .* ori;
  end