mathra

Math LaTeX to accessible SVG, without a TeX install, chemistry (chemfig structures, reaction schemes, mechanisms) and commutative diagrams (tikz-cd, xymatrix) included. Every SVG carries the phrase a screen reader says, in 16 languages, and draws with the STIX Two Math font embedded, so it looks the same everywhere. Try it in the browser.

pip install mathra

Wheels for Linux, macOS and Windows, for Python 3.9 and later; nothing else to install.

Usage

import mathra

svg = mathra.tex_to_svg(r"x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}")
open("quadratic.svg", "w", encoding="utf-8").write(svg)

r = mathra.render(r"\frac{3}{4}", locale="fr")
r["speech"]        # 'trois quarts'
r["warnings"]      # [] — broken LaTeX is drawn anyway and reported here (E-REC-*)

mathra.tex_to_svg(r"\sum_{n=1}^{\infty} \frac{1}{n^2}", display=False)   # inline style
mathra.tex_to_svg(r"\vertA\vert", strict=True)                           # ValueError, like TeX
mathra.render("sqrt(x)/2", input="asciimath")["speech"]                   # also input="mathml"
mathra.render(r"\chemfig{H_3C-*6(=-=-=-)}")["speech"]                     # 'structure of C7 H8, with 1 aromatic ring'

png = mathra.tex_to_png(r"e^{i\pi} + 1 = 0", background="white")           # PNG bytes, 300 dpi
open("euler.png", "wb").write(png)

input is "latex", "mathml" or "asciimath"; MathML passed as LaTeX, starting with <math, is recognized on its own. braille is "cmu" or "nemeth"; by default the locale's (CMU in pt-BR and es, Nemeth elsewhere). tex_to_png is for where SVG is not accepted (e-mail, some editors and LMSs): dpi is over a 12pt body, so an em is dpi * 12 / 72 pixels (50 at 300 dpi), each side rounded up to a whole pixel; background (transparent by default) and color, the ink, are CSS colors, and colors set in the equation keep their own. A PNG is only the drawing, with no speech or source: give it the speech as its alt text. labels and citations give the numbers of the document's cross-references, which an equation converted alone cannot know: with labels={"eq:a": 3} and citations={"knuth": 1}, \eqref{eq:a} shows (3), \ref{eq:a} shows 3 and \cite{knuth} shows [1]; an unknown key is (??), ?? or [?], as on LaTeX's first run, with a warning (a ValueError with strict=True). Errors are ValueError. Types are included (py.typed).

What it draws

Every image below is an SVG written by mathra, on a white card so it reads well on dark pages.

Quadratic formula	Gaussian integral
Matrix with dots	Piecewise definition
Chemistry (\ce)	Units (\SI)
Maxwell's equations
Caffeine (\chemfig)	Commutative diagram (tikz-cd)
Reaction scheme (\schemestart)

Chemistry and diagrams

chemfig works inside any equation: structures (rings, wedges, Lewis marks), reaction schemes (\schemestart … \arrow{->[above][below]} … \schemestop) and mechanism arrows (\chemmove). The speech gives each structure's molecular formula, counted from the drawing. Commutative diagrams come in amscd, tikz-cd and xymatrix. Every construction, drawn live, is in the gallery and the reference.

What the SVG carries

Speech in <title> linked with aria-labelledby, the source equation and the tree of meaning in <metadata>, color from the page (currentColor), size in em, a selectable text layer and ids unique to each equation. The same input always gives the same bytes, in Python and in every other package.

With animate=True the equation writes itself in the browser, with CSS alone: each glyph fades in, each rule grows and each line is drawn, in the order the layout set them, in about three seconds (nothing moves with prefers-reduced-motion); steps=True numbers each element by that order (data-step) with no animation. Both are off by default, and without them the SVG is unchanged byte for byte.

With max_width=30 (in em) an equation wider than that is broken into lines: after a relation (=, ≤, →…), and only when relations alone are not enough, after + and − too, only at its top level (never inside a fraction, a root, \left…\right, scripts or a table). Each line is a <g data-line> of the SVG; speech, text and braille do not change.

Other math fonts

STIX Two Math is embedded and is the default. Any OpenType math font (an .otf or .ttf with a MATH table, such as Libertinus Math or Fira Math) can be loaded from a path or its bytes:

font = mathra.load_font("LibertinusMath-Regular.otf")  # Font(id=0, name='Libertinus Math')
mathra.tex_to_svg(r"e^{i\pi} + 1 = 0", font=font)

A font without a MATH table raises ValueError. The SVG carries the font's outlines, so check that its license allows that.

The fonts of mathfonts, a catalog of math fonts checked with mathra, load by their name. Nothing is downloaded until you ask; a font is downloaded once, kept in ~/.cache/mathra/fonts ($XDG_CACHE_HOME or $MATHRA_CACHE when set, cache= for another folder, cache=False for none) and refused if it does not match the catalog's sha256:

mathra.catalog_fonts()  # [{'slug': 'euler-math', 'name': 'Euler Math', 'license': 'OFL-1.1', ...}, ...]
font = mathra.load_font_from_catalog("euler-math")
mathra.tex_to_svg(r"e^{i\pi} + 1 = 0", font=font)

All the fonts of the catalog are under licenses that let the SVG carry their outlines (OFL, GUST, Apache-2.0, MIT).

Emoji and other characters the math font lacks

Emoji are drawn from Noto Emoji (the monochrome one), embedded in the package: mathra.tex_to_svg("E = mc^2 😀") draws the face, with no warning, in the text color. For other characters the math font lacks, such as Chinese in \text{…}, pass fallback fonts: any .otf or .ttf with outlines, tried in order before Noto Emoji. A math font from load_font can be one too.

cjk = mathra.load_fallback_font("NotoSansSC-Regular.otf")  # FallbackFont(id=0, name='Noto Sans SC')
mathra.tex_to_svg(r"\text{面积} = \pi r^2", fallback_fonts=[cjk])

A character no font has is drawn as a box, with the warning E-REC-8, or raises ValueError with strict=True. Noto Emoji adds about 540 KB to the wheel.

Also for JavaScript, Rust and the terminal

The same core is an npm package (@mathlabs/mathra), a Rust crate and a command-line tool: github.com/matheusmota-dev-br/mathra. Rules, languages and the full list of supported commands are there too.

License

The code is MIT or Apache-2.0; the embedded STIX Two Math and Noto Emoji fonts are under the SIL Open Font License 1.1.