>We know that isn't the case because we can see code being reproduced even with comments
If the comment is something like
//check fromIndex is greater than toIndex
then that is not any more individualistic or different than the actual function. Sadly, many people comment like this, on the other hand if it reproduced a comment with typos or something more complicated like
/* this hack is because Firefox's implementation of SVG z-indexing does not match how Chrome or Safari does it - please read this article ...url...*/
In almost any other scenario this would be evidence. But Fast Inverse Square Root isn’t some tightly held secret. That exact code, with those specific comments included, is found in the Wikipedia page for that algo:
If the comment is something like
//check fromIndex is greater than toIndex
then that is not any more individualistic or different than the actual function. Sadly, many people comment like this, on the other hand if it reproduced a comment with typos or something more complicated like
/* this hack is because Firefox's implementation of SVG z-indexing does not match how Chrome or Safari does it - please read this article ...url...*/
then yeah, then you would have something