One system, one tolerance, and 11 different amounts of work
At its defaults it draws one system, one tolerance, and 11 different amounts of work. Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 10⁴, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 674 to 690, 11 of them distinct, a spread of 2.4% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 6.31·10⁻¹¹ to 1.08·10⁻¹⁰, a factor of 1.72. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
iteration-race is one function in lib/figures/race.js —
what a reduction decides when the decision is discrete — a step count, a rank, and a test's tolerance. 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.
Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 10⁴, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 674 to 690, 11 of them distinct, a spread of 2.4% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 6.31·10⁻¹¹ to 1.08·10⁻¹⁰, a factor of 1.72. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
logKappa: 4
The arguments are the ones A stopping test is a race passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 10⁴, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 674 to 690, 11 of them distinct, a spread of 2.4% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 6.31·10⁻¹¹ to 1.08·10⁻¹⁰, a factor of 1.72. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
logKappa: 2
The arguments are the ones A stopping test is a race passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 100, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 104 to 105, 2 of them distinct, a spread of 1.0% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 7.09·10⁻¹¹ to 8.48·10⁻¹¹, a factor of 1.19. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
logKappa: 3
The arguments are the ones A stopping test is a race passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 1000, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 271 to 277, 4 of them distinct, a spread of 2.2% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 7.12·10⁻¹¹ to 1.12·10⁻¹⁰, a factor of 1.58. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
logKappa: 5
The arguments are the ones A stopping test is a race passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
Conjugate gradients on a 200 × 200 symmetric positive definite matrix with κ = 10⁵, stopped when the relative residual falls below 10⁻¹⁰, run at each of 13 partition counts. The only thing that differs between the runs is how many pieces the two global inner products were summed in — which on a real machine is the number of workers. Iteration counts run from 1641 to 1655, 9 of them distinct, a spread of 0.9% of the work. Every run converged and every answer is right to the accuracy asked for; the forward errors span 7·10⁻¹¹ to 7.43·10⁻¹¹, a factor of 1.06. What differs is not a digit at the end of an answer — it is the bill, and it is an integer.
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.
5 distinct claims across 5 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 conditioning conjugate gradients can finish on
and every answer is correct to the accuracy that was asked for
every run reached the tolerance it was given
LU is for square matrices
matmul shapes agree
Against the rule
It draws a decomposition and prints its residual. It calls
cgAcrossPartitions,
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.