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The IEEE754 standard defines two classes of NaN, the quiet NaN, QNaN, and the signaling NaN, SNaN. When an SNaN is loaded into a floating point register, an exception is raised by the floating point unit. QNaN is available to Delphi code through the constant named NaN that is declared in Math . The definition of that constant is: const NaN = 0.0 / 0.0; I would like to be able to use something similar to declare a constant that is a signaling NaN, but have not yet found a way to do that. Naively you might write this code: function SNaN: Double; begin PInt64(@Result)^ := $7FF7FFFFFFFFFFFF;//this bit pattern specifies an SNaN end; But the ABI for floating point return values means that the SNaN is loaded into a floating point register so that it can be returned. Naturally that leads to an exception which rather defeats the purpose. So you are then led to writing code like this: procedure SetToSNaN(out D: Double); begin PInt64(@D)^ := $7FF7FFFFFFFFFFFF; end; Now, this works, but it's very inconvenient. Suppose you need to pass an SNaN to another function. Ideally you would like to write: Foo(SNaN) but instead you have to do this: var SNaN: Double; .... SetToSNaN(SNaN); Foo(SNaN); So, after the build-up, here's the question. Is there any way to write x := SNaN and have the floating point variable x assigned a value that is a signaling NaN?

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