Low level numerical operation optimizations are often not reproduceable. For example: https://www.intel.com/content/dam/develop/external/us/en/doc... (2013)

But it's still surprising that that LLM doesn't work on iPhone 16 at all. After all LLMs are known for their tolerance to quantization.

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bri3d 4 hours ago | parent [-]

Yes, "floating point accumulation doesn't commute" is a mantra everyone should have in their head, and when I first read this article, I was jumping at the bit to dismiss it out of hand for that reason.

But, what got me about this is that:

* every other Apple device delivered the same results

* Apple's own LLM silently failed on this device

to me that behavior suggests an unexpected failure rather than a fundamental issue; it seems Bad (TM) that Apple would ship devices where their own LLM didn't work.

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sva_ 2 hours ago | parent | next [-]

> floating point accumulation doesn't commute

It is commutative (except for NaN). It isn't associative though.

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ekelsen 39 minutes ago | parent [-]

I think it commutes even when one or both inputs are NaN? The output is always NaN.

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addaon 34 minutes ago | parent [-]

NaNs are distinguishable. /Which/ NaN you get doesn't commute.

	▲	ekelsen 6 minutes ago \| parent [-]
		I guess at the bit level, but not at the level of computation? Anything that relies on bit patterns of nans behaving in a certain way (like how they propagate) is in dangerous territory.

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BeetleB an hour ago | parent | prev | next [-]

As a sister comment said, floating point computations are commutative, but not associative.

a * b = b * a for all "normal" floating point numbers.

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danpalmer 3 hours ago | parent | prev [-]

FYI, the saying is "champing at the bit", it comes from horses being restrained.

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mylifeandtimes an hour ago | parent | next [-]

hey, I appreciate your love of language and sharing with us.

I'm wondering if we couldn't re-think "bit" to the computer science usage instead of the thing that goes in the horse's mouth, and what it would mean for an AI agent to "champ at the bit"?

What new sayings will we want?

	▲	nilamo an hour ago \| parent [-]
		Byting at the bit?

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odo1242 an hour ago | parent | prev [-]

chomping at the bit

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danpalmer an hour ago | parent [-]

Actually it was originally "champing" – to grind or gnash teeth. The "chomping" (to bite) alternative cropped up more recently as people misheard and misunderstood, but it's generally accepted as an alternative now.

	▲	kortilla 2 minutes ago \| parent [-]
		It’s actually accepted as the primary now and telling people about “champing” is just seen as archaic.