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: palm_vtxlabel.m
    path of file: ./repos/CBIG/external_packages/matlab/non_default_packages/palm/palm-alpha109
    
    the code of the file until where you have to start completion: function dpvl = palm_vtxlabel(dpv,fac)
% Label a DPV file (vertexwise data).
% 
% Usage:
% dpvl = palm_vtxlabel(dpv,fac)
% 
% - dpv  : Binary data per vertex to be labelled. The non-zero
%          regions receive an unique identifier.
% - fac  : Face indices (see palm_srfread for details).
% - dpvl : Labelled data per vertex.
% 
% _____________________________________
% Anderson M. Winkler
% FMRIB / Univ. of Oxford
% Feb/2012 (1st version)
% Sep/2013 (this version)
% http://brainder.org

% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
% PALM -- Permutation Analysis of Linear Models
% Copyright (C) 2015 Anderson M. Winkler
% 
% 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 3 of the License, or
% 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, see <http://www.gnu.org/licenses/>.
% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

% For the labelled data
dpvl = zeros(size(dpv));

% Identify faces that are entirely (3 vertices)
% within the supra-threshold vertices. These are
% the only that will be labelled.
facm = reshape(dpv(fac(:)),size(fac));
faci = all(facm,2);

% The strategy below is as follows: at each iteration of the
% loop, it sorts the labels assigned to the 3 vertices of a
% face. If the last vertex, after sorting is zero, then all 3
% are zero, so none was yet labelled. All three then receive
% the current label "k". If, however, the 3rd is non-zero,
% then all three should stay with that label that was assigned
% in an earlier iteration. But before changing the assignment,
% change also all other vertices that have the same label as
% the 1st and 2nd vertices to have the same as the 3rd.
% Then increment the counter.

% For each face
k = 1; % label indices (to be incremented)
for f = find(faci)',

    
function dpvl = palm_vtxlabel(dpv,fac)
% Label a DPV file (vertexwise data).
% 
% Usage:
% dpvl = palm_vtxlabel(dpv,fac)
% 
% - dpv  : Binary data per vertex to be labelled. The non-zero
%          regions receive an unique identifier.
% - fac  : Face indices (see palm_srfread for details).
% - dpvl : Labelled data per vertex.
% 
% _____________________________________
% Anderson M. Winkler
% FMRIB / Univ. of Oxford
% Feb/2012 (1st version)
% Sep/2013 (this version)
% http://brainder.org

% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
% PALM -- Permutation Analysis of Linear Models
% Copyright (C) 2015 Anderson M. Winkler
% 
% 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 3 of the License, or
% 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, see <http://www.gnu.org/licenses/>.
% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

% For the labelled data
dpvl = zeros(size(dpv));

% Identify faces that are entirely (3 vertices)
% within the supra-threshold vertices. These are
% the only that will be labelled.
facm = reshape(dpv(fac(:)),size(fac));
faci = all(facm,2);

% The strategy below is as follows: at each iteration of the
% loop, it sorts the labels assigned to the 3 vertices of a
% face. If the last vertex, after sorting is zero, then all 3
% are zero, so none was yet labelled. All three then receive
% the current label "k". If, however, the 3rd is non-zero,
% then all three should stay with that label that was assigned
% in an earlier iteration. But before changing the assignment,
% change also all other vertices that have the same label as
% the 1st and 2nd vertices to have the same as the 3rd.
% Then increment the counter.

% For each face
k = 1; % label indices (to be incremented)
for f = find(faci)',
    
    % Sort the labels assigned for each face
    flab = sort(dpvl(fac(f,:)));
    if flab(3) == 0,
        
        % If the last is zero, then this is the first time all these
        % vertices are seen, so label them with the current "k".
        dpvl(fac(f,:)) = k;

        % Increment the label counter here, as otherwise the labels
        % are reused.
        k = k + 1;
    else
        % Otherwise, this means that the last (3rd) was seen already
        % and is part of some other label. Assign then this higher label
        % to all other vertices in the surface that may have received,
        % in earlier iterations of the loop, indices that are assigned
        % to the 1st or 2nd vertices of the current face.
        if flab(2) ~= 0;
            dpvl(dpvl == flab(2)) = flab(3);
        end