kernel-cutoff

At its defaults it draws the accuracy of a dot product, either side of a length nobody in the program chose. Mean relative error of a dot product of two vectors whose entries are drawn identically at every length, from 58 to 70 terms, over 40 draws each. Below 64 the kernel accumulates into one register; at 64 and above it uses four independent accumulators and combines them, which is how a tuned library uses a vector unit. The error steps down by 1.57× at the cutoff and is flat either side of it. Nothing about the problem changes there: the vectors are drawn from the same distribution, the arithmetic is the same precision, and the cutoff is a constant in somebody else's source file. A user whose problem grows across it sees the answer move, and there is nothing in their program to look at.

kernel-cutoff is one function in lib/figures/repro.js — one sum, several answers — what a reduction's division costs, and the two policies that remove it. Everything below came out of it during this build, at arguments taken from the essays rather than invented for this page. A figure here is the figure a reader meets in an essay, and if the generator changes, this page changes with it.

Mean relative error of a dot product of two vectors whose entries are drawn identically at every length, from 58 to 70 terms, over 40 draws each. Below 64 the kernel accumulates into one register; at 64 and above it uses four independent accumulators and combines them, which is how a tuned library uses a vector unit. The error steps down by 1.57× at the cutoff and is flat either side of it. Nothing about the problem changes there: the vectors are drawn from the same distribution, the arithmetic is the same precision, and the cutoff is a constant in somebody else's source file. A user whose problem grows across it sees the answer move, and there is nothing in their program to look at.

Mean relative error of a dot product of two vectors whose entries are drawn identically at every length, from 58 to 70 terms, over 40 draws each. Below 64 the kernel accumulates into one register; at 64 and above it uses four independent accumulators and combines them, which is how a tuned library uses a vector unit. The error steps down by 1.57× at the cutoff and is flat either side of it. Nothing about the problem changes there: the vectors are drawn from the same distribution, the arithmetic is the same precision, and the cutoff is a constant in somebody else's source file. A user whose problem grows across it sees the answer move, and there is nothing in their program to look at.

Mean relative error of a dot product of two vectors whose entries are drawn identically at every length, from 26 to 38 terms, over 40 draws each. Below 32 the kernel accumulates into one register; at 32 and above it uses four independent accumulators and combines them, which is how a tuned library uses a vector unit. The error steps down by 1.46× at the cutoff and is flat either side of it. Nothing about the problem changes there: the vectors are drawn from the same distribution, the arithmetic is the same precision, and the cutoff is a constant in somebody else's source file. A user whose problem grows across it sees the answer move, and there is nothing in their program to look at.

Mean relative error of a dot product of two vectors whose entries are drawn identically at every length, from 122 to 134 terms, over 40 draws each. Below 128 the kernel accumulates into one register; at 128 and above it uses four independent accumulators and combines them, which is how a tuned library uses a vector unit. The error steps down by 1.47× at the cutoff and is flat either side of it. Nothing about the problem changes there: the vectors are drawn from the same distribution, the arithmetic is the same precision, and the cutoff is a constant in somebody else's source file. A user whose problem grows across it sees the answer move, and there is nothing in their program to look at.

Every figure above asserted its own claims on the way to being drawn, and a claim that failed would have failed the build rather than drawn a wrong picture. Those assertions used to leave no trace at all: a passing one returned true and the only evidence the figure had checked anything was that nothing crashed. The list below is what they actually said, collected by running this generator with an observer installed — not a description of what it is believed to check.

3 distinct claims across 4 sets of arguments, grouped below by shape — because most of them are one sentence with a different number in it, and how many separate times that sentence was put to the test is the informative part.

The rule does not apply to it. It factorises nothing, so there is no residual it could be withholding. That is worth stating rather than leaving blank: a site that reported the rule as satisfied by every generator would be counting mostly generators the rule never reached.

Across the library: the rule bites on 197 of 363 generators — 179 print a residual and 18 are exempt with a published reason; 166 factorise nothing. Read from lib/residual-rule.js, which is the same body the gate enforces from, and the gate's last check fails the build if this page and it disagree about any generator.