% Element stiffness matrix
function [KE]=lk
E=1.;
nu=0.3;
k=[1/2-nu/6 1/8+nu/8 -1/4-nu/12 -1/8+3*nu/8 ...
    -1/4+nu/12 -1/8-nu/8 nu/6   1/8-3*nu/8];
KE=E/(1-nu^2)*[ k(1)  k(2)  k(3)  k(4)  k(5)  k(6)  k(7)  k(8)  
                k(2)  k(1)  k(8)  k(7)  k(6)  k(5)  k(4)  k(3)
                k(3)  k(8)  k(1)  k(6)  k(7)  k(4)  k(5)  k(2)
                k(4)  k(7)  k(6)  k(1)  k(8)  k(3)  k(2)  k(5)
                k(5)  k(6)  k(7)  k(8)  k(1)  k(2)  k(3)  k(4)
                k(6)  k(5)  k(4)  k(3)  k(2)  k(1)  k(8)  k(7)
                k(7)  k(4)  k(5)  k(2)  k(3)  k(8)  k(1)  k(6)
                k(8)  k(3)  k(2)  k(5)  k(4)  k(7)  k(6)  k(1)];