[J3] [SC22WG5.6473] raising a negative real value to a real power is prohibited

[Jeff Hammond]

Do I understand the following text correctly, that is, that the following program is prohibited, even though it perfectly well-defined mathematically?

“10.1.5.2.4 Evaluation of numeric intrinsic operations

The execution of any numeric operation whose result is not defined by the arithmetic used by the processor is prohibited. Raising a negative real value to a real power is prohibited.”
program main
  implicit none
  real :: x, y
  x = -2.0
  y =  2.0
  print*,x**y
end program main

The first sentence is completely reasonable and seems sufficient to cover the problematic cases.  I do not understand why the second sentence is necessary.

Thanks,

Jeff
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.j3-fortran.org/pipermail/j3/attachments/20230823/e8eff060/attachment.htm>