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: binsurface.m
    path of file: ./repos/iso2mesh
    
    the code of the file until where you have to start completion: function [node,elem]=binsurface(img,nface)
%
% [node,elem]=binsurface(img,nface)
%
% fast isosurface extraction from 3D binary images
%
% author: Qianqian Fang, <q.fang at neu.edu>
%

    
function [node,elem]=binsurface(img,nface)
%
% [node,elem]=binsurface(img,nface)
%
% fast isosurface extraction from 3D binary images
%
% author: Qianqian Fang, <q.fang at neu.edu>
%
% input: 
%   img:  a 3D binary image
%   nface: nface=3 or ignored - for triangular faces, 
%          nface=4 - square faces
%          nface=0 - return a boundary mask image via node
%
% output:
%   elem: integer array with dimensions of NE x nface, each row represents
%         a surface mesh face element 
%   node: node coordinates, 3 columns for x, y and z respectively
%
% the outputs of this subroutine can be easily plotted using plotmesh()
%
% -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
% 

dim=size(img);
if(length(dim)<3)
    dim(3)=1;
end