| InvalidOperationException | either x or y is signaling NaN | 
| OverflowException | result is ±∞ | 
| UnderflowException | result is subnormal or ±0.0 | 
| InexactException | result is ±∞, subnormal or ±0.0 | 
| x | y | nextAfter(x, y) | 
|---|---|---|
| NaN | any | NaN | 
| any | NaN | NaN | 
| x = y | x | |
| x < y | nextUp(x) | |
| x > y | nextDown(x) | 
Returns the next value after or before x, toward y.