In which the CPU changes my data under my nose
troubles.md
troubles.md
Conceptually, the quiet bit is not part of the value. However, I may be missing something obvious about why the writer was trying to control its value.
Is this saying that, on the one hand,
> [A]s far as I can tell x86 and ARM never generate sNaNs, ...
but the CPU can still generate the other kind?
> There we go, that’s a quiet NaN.
It's proving a little hard for me to follow along. My understanding is that this is happening from a floating point number being converted to an integer, back to floating point, then back to an integer again? I think I'm wrong.
I think the point is you can't get the silent bit turned off except by the extreme method of casting arbitrary non-float data. If you deal with floats in the normal way, they are never signalling.
"My understanding is that this is happening from a floating point number being converted to an integer, back to floating point, then back to an integer again?"
The example seems to be integer -> float. The integer is just a bit pattern that happens to mean "signalling NaN" and the author is trying to convert it to a float and unhappy with the "silent" bit/flag changing. I come back to my other comment, that the bit is not really part of the value, so I feel like the concept of equality for the test is what should be fixed.