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: individual2sn.m
    path of file: ./repos/spm12/external/fieldtrip/utilities/private
    
    the code of the file until where you have to start completion: function [warped]= individual2sn(P, input)

% INDIVIDUAL2SN warps the input coordinates (defined as Nx3 matrix) from
% individual headspace coordinates into normalised MNI coordinates, using the
% (inverse of the) warp parameters defined in the structure spmparams.
%
% this is code inspired by nutmeg and spm: nut_mri2mni, nut_spm_sn2def and
% nut_spm_invdef which were themselves modified from code originally written
% by John Ashburner:

    
function [warped]= individual2sn(P, input)

% INDIVIDUAL2SN warps the input coordinates (defined as Nx3 matrix) from
% individual headspace coordinates into normalised MNI coordinates, using the
% (inverse of the) warp parameters defined in the structure spmparams.
%
% this is code inspired by nutmeg and spm: nut_mri2mni, nut_spm_sn2def and
% nut_spm_invdef which were themselves modified from code originally written
% by John Ashburner:
% http://www.sph.umich.edu/~nichols/JohnsGems2.html
%
% Use as
%   [warped] = individual2sn(P, input)
%
% Input parameters:
%   P     = structure that contains the contents of an spm generated _sn.mat
%           file, or the representaiton of the parameters as of SPM12
%   input = Nx3 array containing the input positions

% Copyright (C) 2013-2017, Jan-Mathijs Schoffelen
%
% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
% 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/>.
%
% $Id$

if isfield(P, 'Tr')
  % this is an old-style representation of the parameters, 
  
  % check for a sufficiently recent version of SPM
  if ~ft_hastoolbox('spm')
    % add SPM8 to the path
    ft_hastoolbox('spm8up', 1);
  end