estimator-walk
At its defaults it draws every column's 1-norm on a 12×12 matrix built to stop hager's walk one column short. 12 bars, one per column, each the sum of the absolute values in that column — the quantity the estimator maximises, whose largest is the matrix's 1-norm. The walk visits 1 of them and returns 12.00; column 2 has 1-norm 114.00 and is never visited, because its entries alternate in sign and cancel against every sign vector the walk stands on.
estimator-walk is one function in lib/figures/condest.js —
condition estimation — the number a library prints, and the matrix it flatters. 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.
12 bars, one per column, each the sum of the absolute values in that column — the quantity the estimator maximises, whose largest is the matrix's 1-norm. The walk visits 1 of them and returns 12.00; column 2 has 1-norm 114.00 and is never visited, because its entries alternate in sign and cancel against every sign vector the walk stands on.
n: 12
The arguments are the ones An estimate that can be fooled 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.
12 bars, one per column, each the sum of the absolute values in that column — the quantity the estimator maximises, whose largest is the matrix's 1-norm. The walk visits 1 of them and returns 12.00; column 2 has 1-norm 114.00 and is never visited, because its entries alternate in sign and cancel against every sign vector the walk stands on.
n: 6
The arguments are the ones An estimate that can be fooled 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.
6 bars, one per column, each the sum of the absolute values in that column — the quantity the estimator maximises, whose largest is the matrix's 1-norm. The walk visits 1 of them and returns 6.00; column 2 has 1-norm 26.22 and is never visited, because its entries alternate in sign and cancel against every sign vector the walk stands on.
n: 24
The arguments are the ones An estimate that can be fooled 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.
24 bars, one per column, each the sum of the absolute values in that column — the quantity the estimator maximises, whose largest is the matrix's 1-norm. The walk visits 1 of them and returns 24.00; column 2 has 1-norm 474.24 and is never visited, because its entries alternate in sign and cancel against every sign vector the walk stands on.
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.
8 distinct claims across 4 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 multiplier the construction supports
an even size the bars have room for
an even size, so the alternating column sums to zero
and returns the decoy column's norm
and the walk stopped because its own test fired
so the estimate is less than half the truth
the walk visits a small share of the columns
while the true 1-norm is the alternating column's
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 90
of 174 generators —
75 print a residual and
15 are exempt with a published reason;
84 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.