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 w=[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;