SuperTensor/references/api.md

supertensor.sty API

\documentclass[border=10pt]{standalone}
\usepackage[cjk]{supertensor}     % cjk: ctex + fandol (XeLaTeX). en: English rail labels.

Build with ./scripts/build.sh fig.tex — it puts assets/ on TEXINPUTS, so the package does not need to be installed into your texmf tree.

Ledgers

\stsetrole{q}{stTeal}      % role -> color. Macros take a ROLE, never a color.
\stdim{T}{6}               % symbolic axis -> physical edge length in cells
\stsetauthor{...}          % default 五道口纳什
\stsetlabels{A}{O}{M}      % override the three meaning-box rail labels
\stsetrail{3.2em}          % width of the bold label rail

Colors: stTeal stOrange stCoral stViolet stGray stInk. An unknown role falls back to gray and emits a package warning, which build.sh turns into a failed build.

Lengths: \stunit (one cell, 4.6 mm) and \sttilegap (white gutter, 0.5 mm).

Flow layout

This is the default. Leave the coordinate argument empty and the object is placed by a cursor. Hand-written offsets are the main source of layout bugs in these figures: every gap becomes a tuned magic number, so a label that grows by two characters silently lands on the next tensor, and two stages started from two different x share no rail.

\ststage{SA}{stage heading}      % on the left rail, below the previous band
\strow{rowA}{T}                  % open a band, declared height T
  \stface[role=q]{Q}{}{T}{d}     % empty coord = place at the cursor
  \stglyph{mA}{$\times$}         % operator glyph; reserves its own width
  \stface[role=w]{W}{}{d}{d}
  \stlink{lA}{softmax}           % connector whose LABEL is a flow object
  \stface[role=s]{S}{}{T}{d}
\strowend                        % fit the band, arm the caption lanes
\stcaption{Q}{$\mathbf Q$}{$T\times d$}

macro	does
\ststage{name}{text}	stage heading on the left rail, below all ink so far
\strow{name}{height}	open a band; height is an axis name or an integer
\strowend	fit the band into name, then \stlane it
\stcol{name}{height} … \stcolend	vertical sub-flow filling one slot of the band
\stglyph{name}{$\times$}	operator glyph (not \stop — plain TeX owns that name)
\stcomm{name}{All-Reduce}	collective node
\stnode[style]{name}{text}	any node, placed and measured by the cursor
\stlink{name}{label}	connector; empty label reserves \stlinklen of bare arrow
\stgap{4mm} / \stvgap{4mm}	one-off extra space, horizontal / vertical
\stbbox{all}	everything drawn so far, as one node, for \stmeaningbox
\sttopformula{F}{math}	the formula line, centered on what was actually drawn
\sttrack{node}	fold a hand-placed node into the bbox and the vertical cursor
\stleftrail{x} / \stlayoutreset	move the rail / start over

Gaps are declared once: \stgutter (6 mm, between objects in a band), \strowgap (3.5 mm, above a band), \stblockgap (9 mm, above a stage heading), \stlinklen (10 mm).

Four properties follow by construction, and each of them is a bug class removed:

• The gap belongs to the object that follows it, and the first object in a band gets none — so every band starts flush on the same rail, and gap=0pt means exactly adjacent, which is how shards are made to tile their parent.
• Every object reserves its own width, including a stack's offset sheets and a bracket's overhang. right=6mm of X reserves nothing, so the next face is free to land on top.
• A connector's label is a flow object, so a label can never be wider than its arrow.
• A band declares its height, so an object that does not fit is a build failure (Package supertensor Warning), not something the reader discovers.

Call \sttopformula after the bands. A formula placed first can only be centered on a figure whose width is not yet known — that is how the top line ends up visibly off-center.

\stcol is what a split along the contracted axis looks like:

\stcol{W2}{dff}                              % declared total height
  \stface[role=r1]{W2a}{}{dffl}{d}
  \stface[role=r2, gap=0pt]{W2b}{}{dffl}{d}  % tiles W2a exactly
\stcolend

A column that consumes a height other than the one it declares is drawn off-center, so that is a warning too.

Absolute placement still works everywhere — pass a coordinate instead of {}. Mix freely, but wrap hand-placed nodes in \sttrack so the cursor knows about them.

Faces

\stface[keys]{name}{}{rows}{cols}                    % flow
\stface[keys]{name}{(coord)}{rows}{cols}             % absolute
\ststack[keys]{name}{(coord)}{rows}{cols}{sheets}
\stindexface[keys]{name}{(coord)}{rows}{cols}{entries}

rows/cols accept a declared axis name or a raw integer. A non-empty (coord) must include its own parentheses — {(0,0)}, {($(A.east)+(1.5,0)$)}. name becomes a TikZ node you can anchor against; \ststack also defines name-front.

Keys:

key	default	meaning
role=	neutral	hue, via \stsetrole
pattern=	dense	solid dense diag band lower upper causal empty data
data=	—	with pattern=data: comma-separated rows, one digit per cell, 0–3 = level
level=	2	level for pattern=solid and the flat level of a mask
bracket=	false	thin neutral matrix brackets
border=	true	outer black!60 border
tiles=	true	false = one flat filled rectangle
gap=	\stgutter	flow only: space before this object. gap=0pt = exactly adjacent

\stindexface entries are row-major, rows*cols of them; . leaves a cell blank. It deliberately has no lightness ramp — see semantics.md.

\stface[role=w, pattern=data, level=3,
        data={3300,0330,0033,3003,3030,0303}]{D}{(0,0)}{T}{E}
\stindexface[role=idx]{I}{(b)}{T}{k}{0,1, 1,2, 2,3, 3,0, 0,2, 1,3}

Captions

\strowend calls \stlane for you, so in flow mode captions just follow the band:

\strowend
\stcaption{A}{$\mathbf A$}{$T\times d$}     % symbol lane, shape lane
\stcaptiontop{A}{\stshapefont{token}}       % occasional label above a face

Arming the lane by hand (absolute placement):

\node[inner sep=0pt, fit=(A)(B)(C)] (rowA) {};
\stlane{rowA}
\stcaption{A}{$\mathbf A$}{$T\times d$}
\stnolane

\stcaption defines name-sym and name-shape nodes; anchor the next stage heading against name-shape.south.

Operators, connectors, nodes

Prefer \stglyph / \stcomm / \stlink (above). The raw forms are for absolute placement:

\node[st op, right=6mm of A] (m) {$\times$};   % reserves nothing -- see layout.md
\node[st comm, right=9mm of P] (ar) {All-Reduce};
\starrow{P.east}{ar.west}
\starrowlabel{M.east}{A.west}{softmax}

Styles: st sym st shape st stage st op st note st arrow st comm st brace. Text helpers: \stformula \ststagelabel \stoperator \stsymfont \stshapefont \stprose. Connectors route on the background layer automatically.

Bottom

\stbbox{all}                    % flow: everything drawn so far
\stmeaningbox{mb}{16.6cm}{all}{axes text}{objects text}{mechanism text}
\stsignature{因果多头注意力（掩码 + 拼接投影）}{mb}

Arg 2 is the total box width; arg 3 is the node it hangs below. \stbbox already contains every caption and top label; if you build the fit by hand, include them yourself or the box will overlap them. An empty {} row is dropped.

Gotchas

• \ststack never re-enters \stface; if you extend the package, do not pass role=\st@role back through pgfkeys — it defines the macro in terms of itself and hangs.
• A coordinate expression inside fit= needs braces: fit={(a) ($(b)+(1,0)$)}.
• \foreach {\macro,...,1} cannot infer its direction from an unexpanded macro.
• \strole is expandable on purpose (it is used inside \edef); the warning lives in \stcheckrole.
• Neither the TikZ path parser nor the calc library expands a macro sitting where it expects (. Every cursor-computed coordinate therefore reaches the parser as literal text, via \edef ... \noexpand. Same class of trap: pgfmath cannot digest \stresolve's \ifcsname, so a ledger lookup must be pre-resolved with \edef before it is measured.
• \sttopformula puts a group around its argument, which breaks TikZ's own \\. For more than one line, wrap the math in amsmath's gathered.