One of my more frequent rants, both online and in person, is the danger posed by the "fast-math" compiler flag. While these rants may elicit resigned acknowledgment from those who already understand the dangers involved, they do little to help those who don't. So given the remarkable paucity of writing on the topic (including the documentation of the compilers themselves), I decided it would make a good inaugural topic for this blog. So what is fast-math? It's a compiler flag or option that exis...