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: axis2quat.m
    path of file: ./repos/mtex/geometry/geometry_tools
    
    the code of the file until where you have to start completion: function q = axis2quat(x,y,z,omega)
% rotational axis, roational angle to Quaternion
%
% Decription
%
% defines a rotation by a rotational axis and a roational angle
%
% Syntax
%   q = achs2quat(x,y,z,omega)
%   q = achs2quat(v,omega)
%
% Input
%  x,y,z - rotational axis (double)
%  v     - rotational axis (@vector3d)
%  omega - rotational angle
% Output
%  q - @quaternion
% See also

    
function q = axis2quat(x,y,z,omega)
% rotational axis, roational angle to Quaternion
%
% Decription
%
% defines a rotation by a rotational axis and a roational angle
%
% Syntax
%   q = achs2quat(x,y,z,omega)
%   q = achs2quat(v,omega)
%
% Input
%  x,y,z - rotational axis (double)
%  v     - rotational axis (@vector3d)
%  omega - rotational angle
% Output
%  q - @quaternion
% See also
%  quaternion/quaternion euler2quat Miller2quat vec42quat hr2quat

if nargin == 4
  
  if any(omega(:) > 9)
    warning('The rotation angle appears to be quite large. Maybe you forgot ''* degree'' to switch from degree to radians.');
  end