40 requires requires(T& obj,
typename T::problem_type&
problem,
41 typename T::scalar_type time,
typename T::scalar_type step_size,
42 const typename T::variable_type& variable,
43 typename T::scalar_type solution_coeff) {
45 problem, time, step_size, variable, solution_coeff);
48 requires requires(T& obj,
typename T::variable_type& solution) {