Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Header <boost/numeric/odeint/stepper/controlled_step_result.hpp>

namespace boost {
  namespace numeric {
    namespace odeint {

      // Enum representing the return values of the controlled steppers. 
      enum controlled_step_result { success, fail };
    }
  }
}