delay-branches
At its defaults it draws a spectrum with no last eigenvalue: 12 of the infinitely many solutions of a delay problem. T(λ) = A − λI + 1e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.6·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 4 of them.
delay-branches is one function in lib/figures/nlevp.js —
infinitely many eigenvalues — a contour that counts, and the probe block that is a ceiling. 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.
T(λ) = A − λI + 1e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.6·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 4 of them.
gamma: 1
The arguments are the ones A matrix that depends on its own eigenvalue 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.
T(λ) = A − λI + 1e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.6·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 4 of them.
gamma: 0.5
The arguments are the ones A problem with infinitely many eigenvalues 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.
T(λ) = A − λI + 0.5e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.2·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 4 of them.
gamma: 10
The arguments are the ones A problem with infinitely many eigenvalues 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.
T(λ) = A − λI + 10e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.3·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 4 of them.
gamma: 2
The arguments are the ones A problem with infinitely many eigenvalues 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.
T(λ) = A − λI + 2e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.8·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 6 of them.
gamma: 5
The arguments are the ones Counting what is inside a circle 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.
T(λ) = A − λI + 5e^−λI for the model matrix at n = 4. The problem decouples in A's eigenvector basis, so each of its 4 eigenvalues μ contributes the scalar equation μ − λ + γe^−λ = 0, whose solutions are λ = μ + W_k(γe^−μ) — one for every branch of the Lambert W function, and therefore countably infinitely many, running off to the left along two curves. The marks are the closed form, each checked by substitution to 1.7·10⁻¹⁵. There is no computation that returns this set: the only well-posed question is which eigenvalues lie inside a region, and the circle of radius 4 contains 6 of them.
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.
7 distinct claims across 6 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 contour the picture can hold
a delay coefficient the branches can be found for
a division by a complex number that is not zero
a Lambert argument that is not zero
a size the closed form can be drawn at
a size the contour integrals can afford
every branch value satisfies its own equation
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 173
of 325 generators —
158 print a residual and
15 are exempt with a published reason;
152 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.
A matrix that depends on its own eigenvalue
A damped structure does not produce Ax = λx. It produces (λ²M + λC + K)x = 0, where the matrix whose null vector is wanted is a function of the number being solved for — so there is nothing to factorise, an n × n problem has 2n answers, and the eigenvectors cannot be a basis.
The eigenvalue problem that is not linearA problem with infinitely many eigenvalues
Let the matrix depend on λ through something that is not a polynomial and three things stop being true at once. There is no linearisation, there is no characteristic polynomial, and "compute the spectrum" is not a request that can be granted — the only finite question is how many eigenvalues are inside this circle.
Randomised, and the guarantee that changes kindCounting what is inside a circle
A trace of a matrix nobody wants to form, integrated around a contour, gives an integer — how many eigenvalues are inside. It converges exponentially, it is estimated with random probes, and the probe block is a ceiling that the answer does not mention.
Where the flop count stopped predicting the timeThe last digit is the cheapest
Every cost curve on this site has the same shape: the first digits are cheap and the last ones are not. One method inverts it. Doubling the work buys twice as many digits as the previous doubling did, so the price of a digit halves every time it is paid.