addnodes.m

MATLAB二维电阻抗断层成像算法!用于医学成像,里面包括有限元剖分正问题,及反问题的算法.并且附有网络剖分数据表!

function [g,HH,Indb1]=addnodes(g,H,bg);

%addnodes Adds nodes in the middle of each face of the triangular element 
% Function [g,HH,Indb1]=addnodes(g,H,bg);
% adds nodes in the middle of each edge of the 2D triangular
% element. g includes the coordiates and H the connectivity.
% HH is the new connectivity matrix. New nodes are added at the end
% of the matrix g.
%
% INPUT
%
% g = node coordinates 
% H = connectivity
% bg = indices of the boundary nodes
%
% OUTPUT
%
% g = new node coordinates
% HH = new connectivity 
% Indb1 = indices of the boundary nodes



g2=[];
for ii=1:length(H)
  g1=g(H(ii,:),:);
  g21=(g1(1,:)+g1(2,:))/2;
  g22=(g1(2,:)+g1(3,:))/2;
  g23=(g1(1,:)+g1(3,:))/2;
  g2=[g2;g21;g22;g23];
end

g2=intersect(g2,g2,'rows');
g=[g;g2];
inds=zeros(size(g));

HH=zeros(size(H,1),6);
 for ii=1:size(H,1);
   g1=g(H(ii,:),:);
   g21=(g1(1,:)+g1(2,:))/2;
   g22=(g1(2,:)+g1(3,:))/2;
   g23=(g1(1,:)+g1(3,:))/2;
   H1=find(g(:,1)==g21(1) & g(:,2)==g21(2));
    if find(bg==H(ii,1)) & find(bg==H(ii,2))
      inds(H1)=1;
    end
   H2=find(g(:,1)==g22(1) & g(:,2)==g22(2));
    if find(bg==H(ii,2)) & find(bg==H(ii,3))
      inds(H2)=1;
    end
   H3=find(g(:,1)==g23(1) & g(:,2)==g23(2));
    if find(bg==H(ii,3)) & find(bg==H(ii,1))
      inds(H3)=1;
    end 
   HH(ii,:)=[H(ii,1),H1,H(ii,2),H2,H(ii,3),H3];
 end
 
Indb1=[bg;find(inds)];