How can I position equation numbers to the left side?

[Complex2-Liu]

See tex stackexchange 35497.

I try to use the place function, but the result is strange. When alignment is left + bottom, it seems like the number (hello) is located on the right + top. Why does the direction seem to be reversed? What is the parent container of an euqation number?

The function fixed-content-numbering and left-side-numbering is defined as follows:

#let fixed-content-numbering(..nums) = {
  return "(hello)"
}

#let left-side-numbering(align: left, ..nums) = {
  place(align: align, "(hello)")
}

For now, my workaround is to use move in combination with layout.

[Julian-Wassmann]

Hi,

Your approach with setting the numbering parameter of the equation doesn't work, because the numbering seems to be expected to be always on the right side (at least for text direction left-to-right).

Instead, the best option is to recreate the equation in a show rule. We can turn off the default numbering and provide our custom output, like this:

#show math.equation: eq => {
  // apply custom style only to block equations with numbering enabled
  if eq.block and eq.numbering != none {
    // default numbering of the equation
    let eqCounter = counter(math.equation).at(eq.location())
    let eqNumbering = numbering(eq.numbering, ..eqCounter)
  
    grid(
      // change "0pt" to "auto" to give the numbering its own space on the line
      columns: (0pt, 1fr),
      align(left + horizon)[#eqNumbering],
      // note that "numbering: none" avoids infinite recursion
      math.equation(eq.body, block: true, numbering: none),
    )
  } else {
    // default output for inline equations or without numbering
    eq
  }
}

Interestingly, setting the text direction to right-to-left also seems to do the job, but this is a dangerous approach, because it could result in unexpected behaviour.

#show math.equation: eq => {
  set text(dir: rtl)
  eq
}

Reproduction URL: https://typst.app/project/r9ely_g1bPta8rV9ohR0r0

[Complex2-Liu]

Thanks. Your solution is better than mine. It is better to use a grid rather than move and layout.

[Complex2-Liu]

As of typst 0.11.0, PR #3446, which provides math.equation with an argument number-align, has been merged.