@eq displays inconsistent numbering with the label

[ivaquero]

I use a personal template to display equation numbering based on heading levels (numbering restarts at every heading 2), however, I got inconsistent numbering. So how should I modify the following template section.

#let conf(
    eqnumstyle: "1",
    eqnumsep: ".",
    eqnumlevel: 1,
    doc,
) = {

set math.equation(numbering: equation => locate(loc => {
  	let chapter = counter(heading).at(loc).at(0)

    if eqnumlevel == 2 and counter(heading).at(loc).len() > 1 [
      #let subchapter = counter(heading).at(loc).at(1)
  	  (#numbering("1", chapter)#eqnumsep#numbering("1", subchapter)#eqnumsep#numbering(eqnumstyle, equation))]
    else [
      (#numbering("1", chapter)#eqnumsep#numbering(eqnumstyle, equation))]
    }
    ), supplement: none
  )
}

I labeled a Eq. (1.1), but @eq shows Eq. (2.1) when I use it in a section 2 paragraph, that is to say @eq display numbering where I use @.

Please help, many thanks in advance.

[Julian-Wassmann]

Hi,

If I understand you correctly, your custom equation numbering is working correctly for equations, but not when referenced. The reason for this is that you have to customize the reference function so that it can use the right location (target element, not reference itself) for querying counter(heading).

It makes sense to define a custom equation numbering function which is then used in equation and ref rules. This way, you don't have to define the numbering format twice. Like so:

Custom equation numbering function

#let customEqNumbering(n, loc) = {
  let hCounter = counter(heading).at(loc)
  let chapter = hCounter.at(0)
  let headingNumbering = numbering("1", chapter)
  if hCounter.len() > 1 {
    let subchapter = hCounter.at(1)
    headingNumbering += [.#numbering("1", subchapter)]
  }
  let equationNumbering = numbering("1", n)
  [(#headingNumbering.#equationNumbering)]
}

Math set rule

#set math.equation(
  numbering: n => locate(loc => {
    customEqNumbering(n, loc)
  }),
  supplement: none
)

Equation show rule

// example modified from the docs
#show ref: it => {
  let el = it.element
  if el != none and el.func() == math.equation {
    // Override equation references.
    let loc = el.location()
    let n = counter(math.equation).at(loc).first()
    customEqNumbering(n, loc)
  } else {
    // Other references as usual.
    it
  }
}

Reproduction URL: https://typst.app/project/ryRkf6wzlBYQXU6d4qbBfL

I hope this helps, even if probably late.

[ivaquero]

Thank you so much! You've helped me twice.