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: make_ana.m
    path of file: ./repos/bspm/thirdparty/bramila/external/ISC_toolbox/niftitools
    
    the code of the file until where you have to start completion: %  Make ANALYZE 7.5 data structure specified by a 3D matrix. For RGB24 
%  datatype, an extra dimension for RGB should be inserted immedia
    
function ana = make_ana(varargin)

   ana.img = varargin{1};
   dims = size(ana.img);
   dims = [4 dims ones(1,8)];
   dims = dims(1:8);

   voxel_size = [0 ones(1,3) zeros(1,4)];
   origin = zeros(1,5);
   descrip = '';

   switch class(ana.img)
      case 'uint8'
         datatype = 2;
      case 'int16'
         datatype = 4;
      case 'int32'
         datatype = 8;
      case 'single'
         datatype = 16;
      case 'double'
         datatype = 64;
      otherwise
         error('Datatype is not supported by make_ana.');
   end