variables
  x[2] in (0; 0);
  
function f(x[2])
  return(x(2); -1.*sin(x(1)) + 0.81*cos(x(1))*sin(x(1)) - 0.2*x(2));
end

function v(u[2])
  return u(1)^2 +u(1)*u(2) + 4*u(2)^2;
end
