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Comment by venning | Hacker News Reader

Note, when it says "1.6x faster" what is really means is "1.6 as fast" or "60% faster", or really "operates at 1.6x the speed of the baseline", not "1.6x increase in speed".

For example, when looking at the data for Chrome 48's "arrow" tests [1], the baseline number is 57,858,016 and the traceur number is 91,556,806, which is 158.2% of the baseline, but is reported as "1.6x faster".

I know this seems like semantics, but "1.0x faster" sounds a lot like "twice as fast". (In this case, "1.0x faster" is reported as "identical" [2]).

[1] https://github.com/kpdecker/six-speed/blob/master/data.json#...

[2] https://github.com/kpdecker/six-speed/blob/master/tasks%2Fre...

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This is the convention when talking about speedup in software. 1x speedup means identical time.

[1] https://en.wikipedia.org/wiki/Speedup

I agree based on my experience reading these types of comparisons. I've never thought there was any ambiguity to saying "1.6 times faster." It means performance_1 = performance_0 * 1.6.

If the phrase was "1.6x speedup" then I would agree and not have commented. But the phrase is "1.6x faster", which is a bit ambiguous.

That there is disagreement among the commentariat both ways is indicative of ambiguity. (Though, I am assuming no trolling here.)

While not exactly analogous, try replacing it with a percentage and re-evaluate: What does "60% faster" mean and what does "160% faster" mean?

They did say "1.6x faster", not using the term "speedup" (which is terrible nomenclature too, but that's not the point).

To say that something that's no faster is identical to something that's "1x faster" is a terrible confusion of thought.

It's reasonable to expect that, for example, "1x faster" would mean "for a baseline of 1 operation per second, it's faster by 1 operation per second, i.e. a total of 2 operations per second."

EDIT: Oh god, that's even before I saw the "1.2x slower" entries…

>Note, when it says "1.6x faster" what is really means is "1.6 as fast" or "60% faster", or really "operates at 1.6x the speed of the baseline", not "1.6x increase in speed".

Isn't this always the case with such comparisons? One is meant to multiple initialValue by e.g. 1.6 (hence the "x", for multiple), not calculate initialValue + 1.6*initialValue.

No, the word faster means an increase by that amount. 100% faster means twice as fast. 1x faster means twice as fast. 100% as fast means no change. 1x as fast means no change.

English, you subtle trickster!

I'm not sure I've ever seen anything described as being '1x' faster, without any fractional part. It's such an uncommon usage, I really don't think you can categorically declare that '1x faster means twice as fast'.

If I said A was 50% faster than B which is faster? Because it means the same as A is 0.5x faster than B.

For "A was 50% faster than B", it could very easily be B which is faster -- and A is half its speed.

What I meant to say in my parent comment is not the use of "faster" vs "as fast" in English, but that usually in those benchmarks "Nx" means N times the speed of the baseline.

In English, "50% faster" is unambiguously "1.5x as fast". No one would ever interpret it as meaning that B is faster.

This confused the heck out of me as a kid. Saying something is 50% faster means the same as being 150% faster. Or 100% faster could also be 200%, depending on subtle language choices.

Very unintuitive.

I still don't see how it could be confusing.

"faster than" != "as fast as"

A is 50% faster than B == A is 150% as fast as B

Again, I wasn't talking about what's it in "proper english" -- but how it's used in benchmarks.

Kevin Decker, who did the site in TFA, is a native english speaker, and yet he writes "1.5x faster" to mean baseline1.5 (and not baseline + 1.5baseline).

So clearly it's not so "unambiguous" whether you can use faster in this way or not. And in fact, I've never seen any of those benchmarks where "Nx" doesn't mean the final value is N*baseline.

Not really, that doesn't make sense. It's "0.5x the speed of b". Saying "faster" when it's really actually slower is just confusing and ungrammatical. Likewise saying "1x faster" when it's actually the same speed is gratuitously confusing.

What doesn't make sense? Saying "A is 50% faster than B" is equivalent to "A is 150% as fast as B". Same goes for "A is 0.5x faster than B" which is equivalent to "A is 1.5x as fast as B".

There is a very distinct difference between "faster than" and "as fast as" which should be very clear now.

You're 100% right (2x right?), but I think this is one of those situations like "bimonthly", where people usually intend it to mean twice a month instead of every two months.

It's completely ambiguous with potentially significant costs for misunderstanding, but people refuse to make themselves clear, just because.

Yea in that example it might matter, but I'm seeing places where it's 10x or 100x slower. At that point, it hardly matters.

Correct, at the extremes, the numbers don't matter. But where it says "1.2x slower", it really means "84% of baseline" [1], which might be a bit misleading.

[1] https://github.com/kpdecker/six-speed/blob/master/data.json#...

Thanks Captain Obvious

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