Compare Signaling Exception on NaN
Compares two decimal floating-point values and raises an Invalid Operation exception if either is a quiet or signaling NaN.
long __d64_compare_signaling (_Decimal64, _Decimal64);
long __d128_compare_signaling (_Decimal128, _Decimal128);
If either value is a NaN, normal comparisons using the relational operators (==, !=, <, <=, > and >=) always return false, which raises an exception for a signaling NaN but not for a quiet NaN. If you want an exception to be raised when either value is a quiet or signaling NaN, you should use the Compare Signaling Exception on NaN built-in functions instead of a relational operator.