Numeric presentation without changing values

The document plugin attaches rix.numeric-presentation@1 to existing output nodes. The mathematical tree remains the source of truth. Labels, tables, grids, captions, controls and text alternatives use the same policy in HTML, Markdown, Quarto, LaTeX, SVG, TikZ and Canvas. Child policies replace inherited policies; changing a policy never recalculates a value.

.Plugin.Load("document");
policy := .document.NumericPolicy({= notation=:decimal,decimalPlaces=2 });
report := .document.Present(.Fragment([
    .Paragraph(["Rounded: ",1/3,"; exact override: ",.document.Present(7/3,{= fraction=:mixed })]),
    .Table(["source","descending"],[[1/3,5/3:4/3]])
]),policy);
saved := .document.EncodeJSON(report);
.document.DecodeJSON(saved)[:value];

Present(number, policy) creates an ordinary Text record retaining the number; Present(output, policy) retains the output’s children by reference. The policy and exact source are persisted separately by document JSON and portable bundles. The rounded display is not a replacement for the source record. Include the saved JSON/bundle when values need to be recovered from a publication.

Option Values and limits
notation exact (default), decimal, scientific, engineering, repeating
fraction improper (default) or mixed, using existing 2..1/3 spelling
significantDigits 1–256, default 12
decimalPlaces 0–256 for decimal notation; omitted uses significant digits
rounding nearest-even (default), floor, ceil, toward-zero
locale invariant (default), en-US, de-DE, fr-FR
grouping 0 or 1; default 0
maxPeriod 1–4096, default 1024; finite repeat discovery work

These locale profiles are deterministic display adapters: they do not change RiX parsing, decimal-point syntax, or mathematical identity. Localized display strings need the source record for unambiguous recovery. Scientific notation uses E; repeating decimals use the existing 0.1#6 grammar.

All exact rounding uses integer arithmetic, including very large numerators and denominators. Source integer components are limited to 16,384 digits for this display service. A rounded value carries ≈. Exhausted period discovery falls back to bounded decimal display with [period limit]. Formal Fraction values always retain their original numerator and denominator, including under decimal policies. Existing .Format/_> numeral formatting remains available separately.

Intervals preserve start/end order. Decimal/scientific endpoints round outward, overriding scalar rounding choices; narrow intervals cannot collapse merely because their nearest displays coincide. Certified approximations keep an explicit certified enclosure; ordinary approximate inputs never acquire one. Graphic geometry still uses the coordinate-lowering policy, separately from this label policy. Exact coordinate disclosures retain their source strings.

Control labels may be formatted, but editable expression inputs retain the original source text. Explicit custom control formatters still own nonnumeric labels. This policy does not reinterpret literal strings, code, or TeX math.

Renderer options also accept numericPolicy for one export without changing the saved tree. A persisted node policy overrides that export default.

.Plugin.Load("document"); .Plugin.Load("markdown");
.markdown.Render(.Paragraph([1/3]), {=
    numericPolicy={= notation=:scientific,significantDigits=3 }
}).Get("content");

JavaScript hosts can use createNumericPolicy, withNumericPresentation and presentNumericValue. The latter returns the original value, source spelling, policy, display text, evidence category, rounding/exhaustion flags and interval orientation/outward policy. It returns null for nonnumeric values. Unknown options, invalid versions, excessive limits and nonfinite values fail clearly.

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