math — go-tex

A pure-Go (no cgo) TeX math-mode typesetter → SVG. It parses a subset of TeX math syntax and lays it out to a self-contained <svg> using the OpenType MATH table — via go-opentype for MATH metrics and vector glyph outlines — with no TeX engine, no server, and no cgo. It compiles to GOOS=js/GOARCH=wasm, so it renders math client-side and offline in a browser Web Worker.

This is the math-mode component of the go-tex pure-Go TeX effort; the full engine will live in go-tex/tex.

What it does

Typesets, using real OpenType MATH metrics (axis height, script shifts, fraction rule thickness, script scale-down, …):

• variables as Unicode math-italic; atom-class spacing (TeX Appendix G: thin/medium/thick around operators, relations, punctuation);
• superscripts (^), subscripts (_), and primes ('), with big-operator limits set above/below in display style;
• fractions (\frac, \dfrac, \tfrac) with the rule on the math axis;
• radicals — \sqrt{…} and \sqrt[n]{…} with a stretchy radical sign;
• stretchy delimiters — \left( … \right), [ ], \{ \}, \langle, \lfloor, |, and null ., grown to the content via MATH size variants;
• matrices — matrix, pmatrix, bmatrix, Bmatrix, vmatrix, Vmatrix, and cases;
• accents — \hat \bar \vec \tilde \dot \ddot \check \breve \acute \grave — plus \overline/\underline;
• math alphabets — \mathbb \mathcal \mathfrak \mathbf \mathsf \mathtt \mathit \mathrm (via Unicode math alphanumerics, hole-corrected) and \text;
• ~200 named symbols — Greek, big operators, binary operators, relations, arrows, set/logic; spacing (\, \: \; \! \quad \qquad); and explicit \displaystyle/\textstyle.

\sum_{i=1}^{n} i^2      \sqrt[3]{\frac{a}{b}}      \left(\frac{x+1}{2}\right)^n
\begin{pmatrix} a & b \\ c & d \end{pmatrix}      \mathbb{R} \subset \mathbb{C}

Each renders to a crisp, resolution-independent SVG of positioned glyph paths (with <rect> rules for fractions, radicals and bars). Use RenderDisplaySVG for display style (larger operators, limits above/below).

Install

go get github.com/go-tex/math

Usage

package main

import (
	"fmt"

	texmath "github.com/go-tex/math"
)

func main() {
	// DefaultFont returns an embedded MATH font (STIX Two Math, OFL).
	r, err := texmath.New(texmath.DefaultFont())
	if err != nil {
		panic(err)
	}
	svg, err := r.RenderSVG(`\frac{x^2+1}{\alpha-\beta}`, 40) // 40px base size
	if err != nil {
		panic(err)
	}
	fmt.Println(svg) // <svg …>…</svg>
}

New accepts any OpenType font that carries a MATH table (STIX Two Math, Latin Modern Math, XITS Math, …); DefaultFont embeds STIX Two Math so the zero-config path — and the wasm worker — is self-contained.

WebAssembly

Being pure Go (CGO=0), it compiles to GOOS=js GOARCH=wasm. cmd/wasm is a worker that exposes globalThis.renderMathSVG(tex):

GOOS=js GOARCH=wasm go build -o texmath.wasm ./cmd/wasm

Measured (STIX Two Math embedded): ~1.6 MB gzip worker (most of it the font, which is subsettable), ~0.1–0.3 ms per formula — fast enough to re-render on every keystroke.

Scope — what this is, and is not

This is a math-mode typesetter for preview, not a TeX engine and not a replacement for a TeX distribution (TeXLive). It renders TeX math to SVG; it does not process LaTeX documents — there is no macro expander, no page/line breaking, no packages, no fonts-beyond-the-one-you-pass, and no PDF/DVI output. Full LaTeX is the separate, staged go-tex/tex engine effort.

Within math mode it is broad (see the feature list above). Known limitations: stretchy glyphs use MATH size variants only (not yet the assembly recipe, so delimiters taller than the largest variant stop growing); accent positioning is approximate; and there is no \substack, alignment (aligned/&-columns beyond matrices), or user-defined macros. The symbol table is easy to extend.

Tests

Statement coverage is held at 100% (parser, layout, and error paths), go vet clean, and green across the six 64-bit Go targets plus js/wasm and wasip1/wasm.

go test ./...

Fonts

DefaultFont embeds STIX Two Math, licensed under the SIL Open Font License 1.1 — see STIXTwoMath-OFL.txt. The test-only testdata/nomath.otf is Source Serif 4 (also OFL).

License

BSD-3-Clause — see LICENSE. Copyright the go-tex/math authors. (The embedded font is under its own OFL license, above.)