By default, invalid operations such as division by zero, division by infinity, overflow, and underflow are ignored at run time. However, you can use the -qflttrap option to detect these types of exceptions. In addition, you can add suitable support code to your program to allow program execution to continue after an exception occurs, and to modify the results of operations causing exceptions.
Because, however, floating-point computations involving constants are
usually folded at compile time, the potential exceptions that would be
produced at run time will not occur. To ensure that the -qflttrap option traps all run-time floating-point
exceptions, consider using the -qfloat=nofold
option to suppress all compile-time folding.