meshconn.m

function [conn, connnum, count] = meshconn(elem, nn)
%
% [conn,connnum,count]=meshconn(elem,nn)
%
% create node neighbor list from a mesh
%
% author: Qianqian Fang, <q.fang at neu.edu>
% date: 2007/11/21
%
% input:
%    elem:  element table of a mesh
%    nn  :  total node number of the mesh
%
% output:
%    conn:  output, a cell structure of length nn, conn{n}
%           contains a list of all neighboring node ID for node n
%    connnum: vector of length nn, denotes the neighbor number of each node
%    count: total neighbor numbers
%
% -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
%

conn = cell(nn, 1);
dim = size(elem);
for i = 1:dim(1)
    for j = 1:dim(2)
        conn{elem(i, j)} = [conn{elem(i, j)}, elem(i, :)];
    end
end
count = 0;
connnum = zeros(1, nn);
for i = 1:nn
    if (length(conn{i}) == 0)
        continue
    end
    % conn{i}=sort(setdiff(unique(conn{i}),i));
    neig = unique(conn{i});
    neig(neig == i) = [];
    conn{i} = neig;
    connnum(i) = length(conn{i});
    count = count + connnum(i);
end