[rwallace]

Reasonable people can differ on whether quiet NaN propagation is good or bad, so I don't fault you for being in the latter camp, but I am surprised by your suggestion that it was particularly friendly to 1980s hardware. I was under the impression that an 8087 would have been equally happy to respond to NaN by quiet propagation, setting a global sticky flag or crashing your program, and it's modern hardware, with multiple heavily pipelined vector units running in parallel, that prefers to quietly propagate. Am I missing something?