This is fascinating! I wanted to know more about the history of that function at id, which lead me to this beyond3d post (which was the topic of the reddit post that BetterExplained listed as a source):<p><a href="https:&#x2F;&#x2F;web.archive.org&#x2F;web&#x2F;20070208003255&#x2F;http:&#x2F;&#x2F;www.beyond3d.com&#x2F;articles&#x2F;fastinvsqrt&#x2F;" rel="nofollow">https:&#x2F;&#x2F;web.archive.org&#x2F;web&#x2F;20070208003255&#x2F;http:&#x2F;&#x2F;www.beyond...</a>