Generator

strength-graph

One function in the amg library, called 5 times across 3 essays. Below: what it draws at its defaults, what it draws at every value an essay asks for, the 3 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 strong couplings and the points the matrix kept, ε = 1. A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.

strength-graph is one function in lib/figures/amg.js — algebraic multigrid — a hierarchy with no grid behind it, and what it costs. 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.

Strong couplings and the points the matrix kept, ε = 1A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.the grid the operator came froman edge is a coupling the matrix calls strongkeptinterpolatedwhat the entries decidedcoupling ratio, x against y1strong couplings across x110strong couplings along y110rows kept or dropped whole011×11 grid, θ = 0.25the coarse grid, from the matrix alone

A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.

eps: 0.001

The arguments are the ones Changing the condition number on purpose passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.

Strong couplings and the points the matrix kept, ε = 0.001A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.the grid the operator came froman edge is a coupling the matrix calls strongkeptinterpolatedwhat the entries decidedcoupling ratio, x against y0.001strong couplings across x0strong couplings along y110rows kept or dropped whole1111×11 grid, θ = 0.25the coarse grid, from the matrix alone

A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.

eps: 1

The arguments are the ones The coarse grid the matrix chooses passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.

Strong couplings and the points the matrix kept, ε = 1A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.the grid the operator came froman edge is a coupling the matrix calls strongkeptinterpolatedwhat the entries decidedcoupling ratio, x against y1strong couplings across x110strong couplings along y110rows kept or dropped whole011×11 grid, θ = 0.25the coarse grid, from the matrix alone

A grid of points with lines drawn between the pairs the matrix couples strongly, and the points the coarsening kept drawn larger. At small anisotropy only the vertical lines remain and whole rows are kept.

What it checked while drawing

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 3 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 grid small enough for its couplings to be drawn

and below the threshold the weak one is not strong at all

the strong direction is always strong

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 52 of 99 generators — 37 print a residual and 15 are exempt with a published reason; 47 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.

The whole library · All essays · What must fail