Streamline diffusion alone, and with 0.5 of it across the flow
At its defaults it draws streamline diffusion alone, and with 0.5 of it across the flow. Two bars an angle, on a logarithmic scale. On the axis both are at the level of rounding — the crosswind term costs nothing where the scheme was exact. At 45° the error falls from 0.0661 to 0.0281 and the nodes outside [0, 1] fall from 48 to 0.
crosswind-repair is one function in lib/figures/supg2d.js —
the tuned diffusion in two dimensions — exact along one axis, and the direction it does not go. 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.
Two bars an angle, on a logarithmic scale. On the axis both are at the level of rounding — the crosswind term costs nothing where the scheme was exact. At 45° the error falls from 0.0661 to 0.0281 and the nodes outside [0, 1] fall from 48 to 0.
fraction: 0.5
The arguments are the ones The direction the diffusion does not go passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
Two bars an angle, on a logarithmic scale. On the axis both are at the level of rounding — the crosswind term costs nothing where the scheme was exact. At 45° the error falls from 0.0661 to 0.0281 and the nodes outside [0, 1] fall from 48 to 0.
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.
9 distinct claims across 2 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.
and helps at 15° — checked 3 times
a comparison that includes the aligned case
a crosswind coefficient below the streamline one
a diffusion small enough for a layer
LU is for square matrices
the crosswind term costs nothing on the axis
without adding violations
Against the rule
It draws a decomposition and prints its residual. It calls
solve2d,
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.
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.