Yeah, it' simple to see in this example. Though it's often harder to see in practice, I once heard/read some interesting advice: Test your software in all four

Yeah, it' simple to see in this example. Though it's often harder to see in practice, I once heard/read some interesting advice: Test your software in all four rounding modes. If the software works correctly (and approximately agrees) in all four modes, you're good. (I suppose this assumes that you've got reasonable test coverage.)