Generator

Relative error of scaling and squaring against the number of squarings, μ = 4

One function in the funm library, called 3 times across 2 essays. Below: what it draws at its defaults, what it draws at every value an essay asks for, the 7 claims it put to the test while drawing them, and where it stands against the rule this site is named for.

At its defaults it draws relative error of scaling and squaring against the number of squarings, μ = 4. Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 6·10⁻¹²; the best is 6.88·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.

squaring-cost is one function in lib/figures/funm.js — matrix functions — the definition that is not a method, and the vector that was wanted. 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.

At its defaults

Drawn even though every essay passes arguments — which on this site is every essay, at 100% of placements since the standard pass. A default nothing exercises is a trap for the next essay to call this with none, and this is the page where a default that has drifted from the figures around it becomes visible.

Relative error of scaling and squaring against the number of squarings, μ = 4Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 6·10⁻¹²; the best is 6.88·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.0246810121410⁻¹⁷10⁻¹⁶10⁻¹⁵10⁻¹⁴10⁻¹³10⁻¹²10⁻¹¹10⁻¹⁰10⁻⁹10⁻⁸squarings, srelative error against the closed formbest: s = 2the approximant is out of rangethe squarings amplifyboth sides costerror at s = 06·10⁻¹²best, at s = 26.9·10⁻¹⁶error at s = 153.2·10⁻¹²‖A‖ / 2^s at the best1.1the squarings are exact in the algebraand each one doubles the rounding

Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 6·10⁻¹²; the best is 6.88·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.

mu: 4

The arguments are the ones A coin flip that fixes the average passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.

Relative error of scaling and squaring against the number of squarings, μ = 4Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 6·10⁻¹²; the best is 6.88·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.0246810121410⁻¹⁷10⁻¹⁶10⁻¹⁵10⁻¹⁴10⁻¹³10⁻¹²10⁻¹¹10⁻¹⁰10⁻⁹10⁻⁸squarings, srelative error against the closed formbest: s = 2the approximant is out of rangethe squarings amplifyboth sides costerror at s = 06·10⁻¹²best, at s = 26.9·10⁻¹⁶error at s = 153.2·10⁻¹²‖A‖ / 2^s at the best1.1the squarings are exact in the algebraand each one doubles the rounding

Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 6·10⁻¹²; the best is 6.88·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.

mu: 1

The arguments are the ones The error the method already knows passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.

Relative error of scaling and squaring against the number of squarings, μ = 1Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 4.01·10⁻¹⁵; the best is 2.12·10⁻¹⁶ at s = 1; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.0246810121410⁻¹⁷10⁻¹⁶10⁻¹⁵10⁻¹⁴10⁻¹³10⁻¹²10⁻¹¹10⁻¹⁰10⁻⁹10⁻⁸squarings, srelative error against the closed formbest: s = 1the approximant is out of rangethe squarings amplifyboth sides costerror at s = 04·10⁻¹⁵best, at s = 12.1·10⁻¹⁶error at s = 153.2·10⁻¹²‖A‖ / 2^s at the best0.6the squarings are exact in the algebraand each one doubles the rounding

Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 4.01·10⁻¹⁵; the best is 2.12·10⁻¹⁶ at s = 1; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.

mu: 12

The arguments are the ones The error the method already knows passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.

Relative error of scaling and squaring against the number of squarings, μ = 12Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 5.55·10⁻¹¹; the best is 9.08·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.0246810121410⁻¹⁷10⁻¹⁶10⁻¹⁵10⁻¹⁴10⁻¹³10⁻¹²10⁻¹¹10⁻¹⁰10⁻⁹10⁻⁸squarings, srelative error against the closed formbest: s = 2the approximant is out of rangethe squarings amplifyboth sides costerror at s = 05.6·10⁻¹¹best, at s = 29.1·10⁻¹⁶error at s = 153.2·10⁻¹²‖A‖ / 2^s at the best3the squarings are exact in the algebraand each one doubles the rounding

Each point computes e^(A/2ˢ) by a Padé approximant and squares it s times, against a closed-form exponential. At s = 0 the approximant is being used far outside its range and the error is 5.55·10⁻¹¹; the best is 9.08·10⁻¹⁶ at s = 2; at s = 15 it has risen again to 3.16·10⁻¹². The right-hand rise is the squaring phase amplifying its own rounding, which is why a library chooses s from ‖A‖ rather than taking as many as it can afford.

What it checked while drawing

Every figure above checked its own claims on the way to being drawn, and a claim that failed would have stopped the picture rather than shipped a wrong one. Those checks 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.

7 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.

a size the sweep of exponentials can afford

a superdiagonal the closed form stays representable at

and too many costs as well

LU is for square matrices

matmul shapes agree

the best number of squarings is inside the sweep

too few squarings costs

Against the rule

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 217 of 397 generators — 199 print a residual and 18 are exempt with a published reason; 180 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.

Where it is called

Changing this generator changes every figure on this list. That is what makes the list worth publishing rather than keeping in a check script.

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