Three schemes at ε = 0.005, cell Péclet number 3.13

At its defaults it draws three schemes at ε = 0.005, cell péclet number 3.13. The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 2.4·10⁻¹⁷. Upwinding is smooth and 0.136 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 16 of the 31 points.

tuned-solution is one function in lib/figures/supg.js — tuned diffusion — exact at the nodes, on the problem it was derived from. 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.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 2.4·10⁻¹⁷. Upwinding is smooth and 0.136 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 16 of the 31 points.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 2.4·10⁻¹⁷. Upwinding is smooth and 0.136 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 16 of the 31 points.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 2.4·10⁻¹⁷. Upwinding is smooth and 0.136 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 16 of the 31 points.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 2.8·10⁻¹⁶. Upwinding is smooth and 0.025 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 0 of the 31 points.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 5.6·10⁻¹⁷. Upwinding is smooth and 0.051 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 0 of the 31 points.

The computed solution of each scheme against position, with the exact solution drawn as a dashed line. The tuned scheme's values lie on it — the largest nodal difference is 5.6·10⁻¹⁷. Upwinding is smooth and 0.092 away at its worst. Central differencing oscillates and leaves the interval [0, 1] at 0 of the 31 points.

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.

6 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.

It draws a decomposition and prints its residual. It calls solveScheme, 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 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.