The three unfoldings of a 10 × 11 × 12 smooth tensor, and the singular values of each
At its defaults it draws the three unfoldings of a 10 × 11 × 12 smooth tensor, and the singular values of each. A tensor has one matrix per index — put that index on the rows and every other index down the columns — and each of those matrices has an ordinary rank. Here they are 8, 8, 8 at a relative tolerance of 10⁻⁸, from a tensor of 1320 entries whose modes are of different lengths. Nothing requires the three numbers to agree, and nothing requires any of them to be the tensor's own rank: they are three different matrices built from one array. The leading singular values are 2.37, 2.37, 2.37, each normalised to its own mode below.
unfolding-ranks is one function in lib/figures/tensor.js —
an index that is a tuple — a matrix that is d small ones, and the inverse that is nearly one. 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 tensor has one matrix per index — put that index on the rows and every other index down the columns — and each of those matrices has an ordinary rank. Here they are 8, 8, 8 at a relative tolerance of 10⁻⁸, from a tensor of 1320 entries whose modes are of different lengths. Nothing requires the three numbers to agree, and nothing requires any of them to be the tensor's own rank: they are three different matrices built from one array. The leading singular values are 2.37, 2.37, 2.37, each normalised to its own mode below.
family: "smooth"
The arguments are the ones A decomposition made only of SVDs passes. A value nobody placed would be a picture no essay asked for and no claim was ever checked against.
A tensor has one matrix per index — put that index on the rows and every other index down the columns — and each of those matrices has an ordinary rank. Here they are 8, 8, 8 at a relative tolerance of 10⁻⁸, from a tensor of 1320 entries whose modes are of different lengths. Nothing requires the three numbers to agree, and nothing requires any of them to be the tensor's own rank: they are three different matrices built from one array. The leading singular values are 2.37, 2.37, 2.37, each normalised to its own mode below.
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.
2 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.
a family this site defines
every unfolding has something in it
Against the rule
It draws a decomposition and prints its residual. It calls
modeSvd,
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.
A decomposition made only of SVDs
Everything the definition of tensor rank loses comes back if the SVD's algorithm is carried across instead of its definition — take the leading left singular subspace of every unfolding and project onto all of them. It exists, it costs d matrix decompositions, and its error is within √d of the best there is.
When the index is a tupleA factorisation that is unique for once
A rank-r factorisation of a matrix is never unique — AB is (AM)(M⁻¹B) for any invertible M, so no factor means anything on its own. For three indices a checkable condition on the factors' k-ranks makes the decomposition unique up to permuting and scaling the terms, and it holds generically.