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: qrdivide.m
    path of file: ./repos/VAD/lib/matlab/voicebox
    
    the code of the file until where you have to start completion: function q=qrdivide(q1,q2)
%QRDIVIDE divdes two real quaternions q=[q1,q2]
%
% Inputs:
%
%     q1(4,1), q2(4,1)  Two real quaternions in the form [r, i, j, k]' where i^2=j^2=k^2=ijk=-1
%
% Outputs: 
%

    
function q=qrdivide(q1,q2)
%QRDIVIDE divdes two real quaternions q=[q1,q2]
%
% Inputs:
%
%     q1(4,1), q2(4,1)  Two real quaternions in the form [r, i, j, k]' where i^2=j^2=k^2=ijk=-1
%
% Outputs: 
%
%     q(4,1)   Quotient of q1/q2 such that q1=q*q2.
%              Note that q*q2 ~= q2*q since quaternion multiplication does not commute.

%      Copyright (C) Mike Brookes 2000-2008
%      Version: $Id: qrdivide.m 713 2011-10-16 14:45:43Z dmb $
%
%   VOICEBOX is a MATLAB toolbox for speech processing.
%   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%   This program 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 2 of the License, or
%   (at your option) any later version.
%
%   This program 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 can obtain a copy of the GNU General Public License from
%   http://www.gnu.org/copyleft/gpl.html or by writing to
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
persistent a b c d
if isempty(a)
    a=[5 8 9 10 15 13];
    b=[6 7 11 12 14 16];
    c=[1 2 3 4 6 7 11 12 16 14];
    d=[1 2 3 4 5 8 9 10 13 15];
end