function Mv=Mfun2(v,At,nu)
  n=length(v)/3;
  w1=At\v(1:n);
  w2=At\w1;
  w3=At\v(n+1:2*n);
  z1=-w2+w3;
  z3=-(w2+w3+v(2*n+1:3*n))./nu;
  z2=At\z3;
  Mv=[z1-At\z2;w1+z2;z3];
end