Universe

A Typst package enabling support for Unicode super- and subscript characters in equations.

Usage

The package exposes the template-function super-subscripts. It affects all math.equations by attaching every superscript- and subscript-character to the first non-space-element on its left.

#import "@preview/super-suboptimal:0.1.0": *
#show: super-subscripts

For all $(x,y)∈ℝ²$:
$
  q := norm((x,y))₂ < 1
  ==> ∑ᵢ₌₁ⁿ q ⁱ < ∞
$

Rendering of above code

Because code like $x+yᶻ$ throws an “unknown variable” error, the package also exposes the function eq, which inserts spaces before every superscript- and subscript-character and passing it on to math.equation. This comes at the cost of missing syntax-highlighting and code-suggestions in your IDE.

eq accepts a raw string as a positional parameter, and an argument-sink that’s passed onto math.equation. Unless specified otherwise in the argument-sink, the resulting equation is typeset with block: true if and only if the raw also satisfied block: true. eq is automatically applied to every raw with lang: "eq".

#eq(`0 = aᵇ`)

#eq(```
  1 = x+yᶻ
```)

#eq(`2 = aᵇ`, block: true, numbering: "(1)")

```eq
  3 = aᵇᶜ⁺ᵈ₃ₑ⁽ᶠ⁻ᵍ⁾ₕᵢ
```

Rendering of above code

Sometimes in mathematical writing, variables are decorated with an asterisk, e.g. $x^*$. The character ꙳ can now be used, as well: $x꙳ = x^*$.

Known issues

  • As mentioned above, $aᵇ$ leads to an “unknown variable” error. As a workaround, $a ᵇ$ produces the same output, or you can use the eq function described above.

    • The first workaround also means I can’t reasonably implement top-left and bottom-left attachments. For example, $a ³b$ is rendered like $attach(a, t: 3) b$, rather than $a attach(b, tl: 3)$.

  • Multiple attachments are concatenated into one content without another pass of equation. For example, #eq(`0ˢⁱⁿ⁽ᵏ⁾`) is equivalent to $0^(s i n "(" k ")")$, rather than $0^sin(k)$. I won’t fix this, because:

    • Another pass of equation would cause performance issues at best, and infinite loops at worst.
    • If this were fixed, code such as $e ˣ ʸ$ would undesirably produce an “unknown variable xy” error.

  • Let’s call a piece of content “small” if it consists of only a single non-separated sequence of characters in Typst (internally, this is the distinction between the content-functions sequence and text). For instance, $1234$ and $a$ constitute “small” content, but $a b$ and $3a$ and $1+2+3+4+5$ do not.

    This package only runs on non-“small” pieces of content. For example, $sqrt(35²)$ still renders with the default-Unicode-character and will look different from $sqrt(35^2)$. On the other hand, $sqrt(a⁶)$ is rendered correctly. This is because 35² constitutes “small” content, but a⁶ does not.

    A workaround is implemented for “small” content immediately within an equation, i.e. not nested within another content-function. For example, $7²$ renders the same as $7^2$, even though it’s “small” content.

  • Equations within other content-elements might trigger multiple show-rule-passes, possibly causing performance-issues.