D1num D1num_sub IsFinite IsFinite_sub IsInf IsInf_sub IsNan IsNan_sub IsNormal IsNormal_sub Signbit Signbit_sub

IsNan_sub() Sub IsNan_sub ( Ret As  Boolean, X As  Double  ) Determine if NaN (Not-a-Number) value (Subroutine version) Purpose Determines if the given argument has NaN (Not-a-Number) value. Parameters [out] Ret If X has NaN value, True is returned. Otherwise, False is returned. [in] X Argument to be examined.