in reply to When 1e-298L != 1e-298L

unpack "b64", pack "D", 1e-298;

I suspect - but cannot verify as MSC maps long double to double -- that (a part of) the problem is the way you are inspecting the values.

On intel, gcc maps long double to an 80-bit floating point number -- though it may store it in either 12- or 16-bytes for alignment -- and you are only inspecting 64-bits of that 80-bit value.

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