function int=grinprodgaus(g,sigma);%grinprodgaus Computes the integral of the product of the gradients in 2D FEM% The function int=grinprodgaus(g,sigma);% calculates the gradient part in the linear % FEM in 2D EIT.%% INPUT%% g = nodal coordinates% sigma = conductivity of the element%% OUTPUT%% int = value of the integral % P. Ronkanen and M. Vauhkonen 10.5. 1996% University of Kuopio, Department of Applied Physics, PO Box 1627,% FIN-70211 Kuopio, Finland, email: Marko.Vauhkonen@uku.fiw=[1/6*ones(3,1)];ip=[1/2 0;1/2 1/2;0 1/2];L=[-1 1 0;-1 0 1];Jt=L*g;iJt=inv(Jt);dJt=abs(det(Jt));G=iJt*L;%int=0;% for ii=1:3%  int=int+w(ii)*G'*G;% end%int=sigma*int*dJt;int=1/2*sigma*G'*G*dJt;