surfacenorm

 snorm=surfacenorm(node,face)
    or
 snorm=surfacenorm(node,face,'Normalize',0)

 compute the normal vectors for a triangular surface

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

 input:
   node: a list of node coordinates (nn x 3)
   face: a surface mesh triangle list (ne x 3)
   opt: a list of optional parameters, currently surfacenorm supports:
        'Normalize': [1|0] if set to 1, the normal vectors will be 
                           unitary (default)

 output:
   snorm: output surface normal vector at each face

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

0001 function snorm=surfacenorm(node,face,varargin)
0002 %
0003 % snorm=surfacenorm(node,face)
0004 %    or
0005 % snorm=surfacenorm(node,face,'Normalize',0)
0006 %
0007 % compute the normal vectors for a triangular surface
0008 %
0009 % author: Qianqian Fang, <q.fang at neu.edu>
0010 %
0011 % input:
0012 %   node: a list of node coordinates (nn x 3)
0013 %   face: a surface mesh triangle list (ne x 3)
0014 %   opt: a list of optional parameters, currently surfacenorm supports:
0015 %        'Normalize': [1|0] if set to 1, the normal vectors will be
0016 %                           unitary (default)
0017 %
0018 % output:
0019 %   snorm: output surface normal vector at each face
0020 %
0021 % -- this function is part of iso2mesh toolbox (http://iso2mesh.sf.net)
0022 %
0023 
0024 opt=varargin2struct(varargin{:});
0025 
0026 snorm=surfplane(node,face);
0027 snorm=snorm(:,1:3);
0028 
0029 if(getoptkey('Normalize',1,opt))
0030     snorm=snorm./repmat(sqrt(sum(snorm.*snorm,2)),1,3);
0031 end