uniqedges

 [edges,idx,edgemap]=uniqedges(elem)

 return the unique edge list from a surface or tetrahedral mesh

 author: Qianqian Fang, <q.fang at neu.edu>

 input:
     elem: a list of elements, each row is a list of nodes for an element.
           elem can have 2, 3 or 4 columns

 output:
     edge: unique edges in the mesh, denoted by a pair of node indices
     idx:  index of the output in the raw edge list (returned by meshedge)
     edgemap: index of the raw edges in the output list (for triangular mesh)

 -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)

0001 function [edges,idx,edgemap]=uniqedges(elem)
0002 %
0003 % [edges,idx,edgemap]=uniqedges(elem)
0004 %
0005 % return the unique edge list from a surface or tetrahedral mesh
0006 %
0007 % author: Qianqian Fang, <q.fang at neu.edu>
0008 %
0009 % input:
0010 %     elem: a list of elements, each row is a list of nodes for an element.
0011 %           elem can have 2, 3 or 4 columns
0012 %
0013 % output:
0014 %     edge: unique edges in the mesh, denoted by a pair of node indices
0015 %     idx:  index of the output in the raw edge list (returned by meshedge)
0016 %     edgemap: index of the raw edges in the output list (for triangular mesh)
0017 %
0018 % -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
0019 %
0020 
0021 if(size(elem)==2)
0022    edges=elem;
0023 elseif(size(elem)>=3)
0024    edges=meshedge(elem);
0025 else
0026    error('invalid input');
0027 end
0028 
0029 [uedges,idx,jdx]=unique(sort(edges,2),'rows');
0030 edges=edges(idx,:);
0031 if(nargout>2)
0032     edgemap=reshape(jdx,[size(elem,1) nchoosek(size(elem,2),2)]);
0033 end