> Given how murky signaling NaNs are in practice, I think it's worth > asking: why do you want to know?
Because I am writing an implementation of the IEEE support modules in GNU Fortran, which are part of the Fortran 2003 standard. And the standard provides for a procedure (IEEE_CLASS) to distinguish between IEEE_SIGNALING_NAN and IEEE_QUIET_NAN. It doesn’t explicitly state that supporting sNaN is required, so I can also just not return it. FX
