integrofgrad.sci

用来实现三维阻抗及光学断层成像重建的matlab程序

function [IntGrad]=integrofgrad(vtx,%simp,mat_ref)
IntGrad=[];
//function [IntGrad] = integrofgrad(vtx,simp,mat_ref);
// 
//function that calculates the integral of the gradients for first order 
//tetrahedral elements. Required for the calculation of the Jacobian. 
// 
// 
// 
//vtx     = The vertices matrix
//simp    = The simplices matrix
//mat_ref = The reference conductivity vector
//IntGrad = The intgral of the gradients
 
 
 
[vr,vc] = size(vtx);
[sr,sc] = size(%simp);
 
 
//! unknown arg type, using mtlb_length 
if sr~=mtlb_length(mat_ref) then
  error('Mismatched data entered');
end
 
if sc~=4 then
  error('Only first order tetrahedral elements supported');
end
 
 
//w = [1/24*ones(4,1)];
 
IntGrad = sparse([],[],[vr^2,sr]);
 
for i = 1:size(%simp,1)
   
  vv = [];
   
  for j = 1:size(%simp,2)
    vv = [vv;vtx(%simp(i,j),:)];
  end
   
  interp_fun = [-1,1,0,0;-1,0,1,0;-1,0,0,1];
   
  Jts = interp_fun*vv;
  inv_Jts = inv(Jts);
  det_Jts = abs(det(Jts));
   
  Gs = inv_Jts*interp_fun;
   
  //int = 0;
  //for q=1:4
  //  int = int + w(q)*Gs'*Gs;
  //end
  //Inte = int*det_Jts; % or simplified
  // Citation: The FEM displayed G.Dhatt & G. Touzot
   
  Inte = 1/6*Gs'*Gs*det_Jts;
   
  Local = sparse([],[],[vr,vr]);
  Local(%simp(i,:),%simp(i,:)) = Inte;
  IntGrad(:,i) = Local(:);
end
 
 
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
// This is part of the EIDORS suite.
// Copyright (c) N. Polydorides 2001
// Copying permitted under terms of GNU GPL
// See enclosed file gpl.html for details.
// EIDORS 3D version 1.0
// MATLAB version 5.3 R11
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%