<notatio-contour-plot>

Parse a JSON attribute defensively -- an empty/invalid value reads as undefined. */ function parseJson(value: string): unknown { const text = value.trim(); if (!text) return undefined; try { return JSON.parse(text); } catch { return undefined; } }

const log = debug("contourplot");

const isNumber = (v: unknown): v is number => typeof v === "number" && Number.isFinite(v);

/** A 2-D numeric matrix (for data, the ListContourPlot path). */ function toMatrix(data: unknown): number[][] | undefined { if (!Array.isArray(data) || data.length === 0 || !data.every((r) => Array.isArray(r))) return undefined; const rows = (data as unknown[][]).map((r) => r.filter(isNumber)); return rows.every((r) => r.length === rows[0].length) ? rows : undefined; }

/** <notatio-contour-plot expr="x^2 - y^2" xrange="-3,3" yrange="-3,3"> -- the contour lines of a bivariate expression (Wolfram's ContourPlot): the expression is sampled on an n×n grid over xrange/yrange (substituting the two free variables) and iso-lines are extracted at several levels via marching squares. levels accepts either a level count or an explicit JSON array of level values; omitted, ~8 evenly spaced levels are chosen between the sampled min and max. filled shades the bands between levels with a sequential ramp instead of drawing lines. data (a JSON 2-D array) plots a pre-sampled grid directly, skipping expression evaluation (ListContourPlot).

Stories in the playground·packages/notatio-lit/src/notatio-contour-plot.ts· in Vue: <ContourPlot>

Attributes

Attribute	Type	Default	Notes
expr	string	""	The bivariate expression, in notatio.
xvar	string	""	The variable on the x axis; defaults to the expression's first unknown.
yvar	string	""	The variable on the y axis; defaults to the next unknown after xvar.
xrange	string	"-3,3"	The x sampling range, as lo,hi.
yrange	string	"-3,3"	The y sampling range, as lo,hi.
n	number	40	Grid resolution per side.
levels	string	""	A contour count, or an explicit JSON list of level values.
filled	string	"false"	Anything but "false" shades the bands between contours.
axes	string	"true"	"false" hides the axes.
x-label property xLabel	string	""	Axis label for x.
y-label property yLabel	string	""	Axis label for y.
label	string	""	Caption drawn above the figure.
data	string	""	A pre-sampled grid as a JSON matrix, plotted instead of expr.