contour-recovery
At its defaults it draws 4 eigenvalues inside a circle of radius 4, and 2 moments to reach them. A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 2 contour moments against a probe block of 2 recover, agreeing to 2.16·10⁻¹². With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
contour-recovery is one function in lib/figures/beyn.js —
a ceiling with a knob on it — higher contour moments, and the conditioning that rises with them. 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 2 contour moments against a probe block of 2 recover, agreeing to 2.16·10⁻¹². With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
radius: 4
The arguments are the ones A ceiling with a knob on it 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 2 contour moments against a probe block of 2 recover, agreeing to 2.16·10⁻¹². With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
radius: 2
The arguments are the ones A ceiling with a knob on it 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 1 contour moment against a probe block of 2 recover, agreeing to 2.44·10⁻¹⁵. With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
radius: 3
The arguments are the ones A ceiling with a knob on it 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 2 contour moments against a probe block of 2 recover, agreeing to 7.11·10⁻¹⁵. With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
radius: 5
The arguments are the ones A ceiling with a knob on it 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 6 contour moments against a probe block of 2 recover, agreeing to 5.02·10⁻¹⁴. With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
radius: 6
The arguments are the ones A ceiling with a knob on it 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.
A delay eigenvalue problem T(λ) = A − λI + e^{−λ}I, which has infinitely many eigenvalues and no linearisation, so the only finite question is what lies inside a given contour. The crosses are the Lambert-W closed form λ = μ + W_k(γe^{−μ}), one per eigenvalue of A per branch; the discs are what 6 contour moments against a probe block of 2 recover, agreeing to 4.22·10⁻¹³. With one moment the method could have returned at most 2 of them and would have said nothing about the rest.
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.
10 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 closed form covers
a contour with something inside it
a division by a complex number that is not zero
a Lambert argument that is not zero
a probe block the contour can afford
a size the contour integrals can afford
enough moments for the block asked for
every eigenvalue inside the contour is found
LU is for square matrices
matmul shapes agree
Against the rule
It draws a decomposition and prints its residual. It calls
contourMoments, momentEigenvalues,
and every figure above carries the badge — which residualcheck verifies by looking
for it in the emitted SVG rather than by finding the call that builds one. A badge that is
constructed and then left out of the body is the failure that check exists for.
Across the library: the rule bites on 192
of 346 generators —
174 print a residual and
18 are exempt with a published reason;
154 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 ceiling with a knob on it
A contour method returns at most as many eigenvalues as its probe block has columns, and the object that comes back does not distinguish that from having found everything. One line of the derivation multiplies the ceiling by a number the caller chooses, and it costs no extra solves at all.
The eigenvalue problem that is not linearThe conditioning that rises with the ceiling
Higher moments multiply a contour method's ceiling by K and grade its block Hankel over ρ to the 2K, so the two knobs are the same knob. One division per quadrature point separates them, and the measurement of what it is worth grows from twenty to twenty thousand.
The eigenvalue problem that is not linearThe eigenvalues that are answers to nothing
A rational approximant of degree five turns a six-by-six problem into a thirty-six-by-thirty-six one, and thirty-six numbers come back. Six are the answer. The rest are exact eigenvalues of the approximant, lying where the function it approximates is not a real number at all.