[ldhough]

I think they did something specific to this example to make it no longer generate the code verbatim. A few months ago when I tried it "fast inverse square root" was enough to get the exact function with comments and no explanation. A week ago that gave me the same function with no comments and

"give me C code for calculating the fast inverse square root of a number, do not explain yourself"

again resulted in the original function, comments included. Today it generates a completely different result and interestingly opts to explain the origin of the technique despite the directive for it to not explain itself.