function A = Assembly(nv, nc, conec, C)
   A = zeros(nv);
   for k=1:nc
     p = conec(k,1);
     q = conec(k,2);
     A(p,p) = A(p,p) + C(k);
     A(p,q) = A(p,q) - C(k);
     A(q,p) = A(q,p) - C(k);
     A(q,q) = A(q,q) + C(k);
   end
end