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: bti2grad.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8/external/fieldtrip/fileio/private
    
    the code of the file until where you have to start completion: function [grad, elec] = bti2grad(hdr, balanceflag)

% BTI2GRAD converts a 4D header to a gradiometer structure that can be
% understood by FieldTrip and Robert Oostenveld's low-level forward and
% inverse routines. This function only works for headers that have been
% read using the READ_4D_HDR function.
%
% Use as:
%   [hdr]  = read_4d_hdr(filename)
%   [grad] = bti2grad(hdr)
%
% or
%
%   [hdr]  = read_4d_hdr(filename)
%   [grad, elec] = bti2grad(hdr)
%
% This function only computes the hardware magnetometer definition
% for the 4D system. This function is based on ctf2grad and Gavin
% Paterson's code, which was adapted from Eugene Kronberg's code
%
% See also CTF2GRAD, FIF2GRAD, MNE2GRAD, ITAB2GRAD, YOKOGAWA2GRAD,
% FT_READ_SENS, FT_READ_HEADER

% Copyright (C) 2008, Jan-Mathijs Schoffelen
%
% This file is part of FieldTrip, see http://www.ru.nl/neuroimaging/fieldtrip
% for the documentation and details.
%
%    FieldTrip is free software: you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    FieldTrip is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
%
% $Id: bti2grad.m 7123 2012-12-06 21:21:38Z roboos $

% for backward compatibility issues FIXME check whether anyone actually uses this code
if isfield(hdr, 'Meg_pos'),
  warning('using outdated code. this does not necessarily lead to correct output');
  
  elec      = [];

    
function [grad, elec] = bti2grad(hdr, balanceflag)

% BTI2GRAD converts a 4D header to a gradiometer structure that can be
% understood by FieldTrip and Robert Oostenveld's low-level forward and
% inverse routines. This function only works for headers that have been
% read using the READ_4D_HDR function.
%
% Use as:
%   [hdr]  = read_4d_hdr(filename)
%   [grad] = bti2grad(hdr)
%
% or
%
%   [hdr]  = read_4d_hdr(filename)
%   [grad, elec] = bti2grad(hdr)
%
% This function only computes the hardware magnetometer definition
% for the 4D system. This function is based on ctf2grad and Gavin
% Paterson's code, which was adapted from Eugene Kronberg's code
%
% See also CTF2GRAD, FIF2GRAD, MNE2GRAD, ITAB2GRAD, YOKOGAWA2GRAD,
% FT_READ_SENS, FT_READ_HEADER

% Copyright (C) 2008, Jan-Mathijs Schoffelen
%
% This file is part of FieldTrip, see http://www.ru.nl/neuroimaging/fieldtrip
% for the documentation and details.
%
%    FieldTrip is free software: you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    FieldTrip is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License
%    along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
%
% $Id: bti2grad.m 7123 2012-12-06 21:21:38Z roboos $

% for backward compatibility issues FIXME check whether anyone actually uses this code
if isfield(hdr, 'Meg_pos'),
  warning('using outdated code. this does not necessarily lead to correct output');
  
  elec      = [];
  grad      = [];
  grad.unit = 'm';
  grad.coilpos  = hdr.Meg_pos;
  grad.coilori  = hdr.Meg_dir;
  for i=1:size(grad.coilpos,1)
    % grad.label{i} = sprintf('MEG%03d', i);
    grad.label{i} = sprintf('A%d', i); % according to BTi convention
  end