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: icatb_eeg_sph2topo.m
    path of file: ./repos/gift/GroupICAT/icatb/toolbox/eegiftv1.0c/icatb_eeglabv6.0b_files
    
    the code of the file until where you have to start completion: % icatb_eeg_sph2topo() - Convert from a 3-column headplot file in spherical coordinates
% 
    
function cart2sph(). Default is 2
%
% Outputs:
%   channo  = channel number (as in input)
%   angle   = horizontal angle (0 -> nose; 90 -> right ear; -90 -> left ear)
%   radius  = arc_lengrh from vertex (Note: 90 deg az -> 0.5/shrink_factor);
%             By topoplot() convention, radius=0.5 is the nasion-ear_canal plane.
%             Use topoplot() 'plotrad' to plot chans with abs(az) > 90 deg.
%
% Author: Scott Makeig & Arnaud Delorme, SCCN/INC/UCSD, La Jolla, 6/12/98 
%
% See also: cart2topo(), topo2sph()

%123456789012345678901234567890123456789012345678901234567890123456789012

% Copyright (C) 6/12/98 Scott Makeig, SCCN/INC/UCSD, scott@sccn.ucsd.edu
%
% 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 should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

% $Log: icatb_eeg_sph2topo.m,v $
% Revision 1.5  2004/03/22 03:42:12  scott
% shrink_factor help message
%
% Revision 1.4  2002/06/29 22:57:23  arno
% changing default for method
%
% Revision 1.3  2002/06/29 01:25:56  arno
% updating header for besa compatibility
%
% Revision 1.2  2002/05/02 00:52:36  arno
% removing absolute value for compatibility
%
% Revision 1.1  2002/04/05 17:36:45  jorn
% Initial revision
%

% corrected left/right orientation mismatch, Blair Hicks 6/20/98
% changed name sph2pol() -> icatb_eeg_sph2topo() for compatibility -sm
% 01-25-02 reformated help & license -ad 
% 01-25-02 changed computation so that it works with icatb_eeg_sph2topo -ad 

function [channo,angle,radius] = icatb_eeg_sph2topo(input,factor, method)

chans = size(input,1);
angle = zeros(chans,1);
radius = zeros(chans,1);

if nargin < 1
   help icatb_eeg_sph2topo
   return
end