How to include section number in equation numbering and removn parenthesis when referencing the equation?

[Lukers]

Hi,

I am trying to use a custom numbering for my equations that includes the current chapter. Using the default numbering

#set page(numbering: "1")
#set heading(numbering: "1.")
#set math.equation(numbering: "(1)")

= First Chapter

= Second Chapter
@Equation is my equation.
$ a^2 + b^2 = c^2 $
<Equation>

Results in:

The number after the equation is in parentheses while the reference in the text is shown without parentheses. When I try to include the section number in the equation numbering like this:

#set page(numbering: "1")
#set heading(numbering: "1.")

#show heading.where(level: 1): it => {
 counter(math.equation).update(0)
 it
}

#set math.equation(
 numbering: n => {
  let section = counter(heading).get().at(0)
  numbering("(1.1)", section, n)
 },
)

= First Chapter

= Second Chapter
@Equation is my equation.
$ a^2 + b^2 = c^2 $
<Equation>

I get:

Which is almost what I want, but now the reference in the text includes the parentheses, so it says “Equation (2.1)” instead of “Equation 2.1”.

When I change this line:

numbering("(1.1)", section, n)

to

numbering("1.1", section, n)

in the text it says “Equation 2.1” like I want it to but the label after the equation itself is changed to “2.1” and is no longer in parentheses.

My question is: Is there a way to get the label to say “(2.1)” while in the text the equation is referenced as “Equation 2.1”?

I have found some related questions and answers here but none of the solutions produce the result I want.

[Y.D.X]

Hi, welcome to the forum!

Does this work for you?

#set page(width: 30em)

#set heading(numbering: "1.1")
#show heading.where(level: 1): it => {
 counter(math.equation).update(0)
 it
}

#set math.equation(
  numbering: n => numbering(
    "(1.1)",
    counter(heading).get().first(),
    n,
  ),
)

#show ref: it => {
  let el = it.element
  if el != none and el.func() == math.equation {
    let loc = el.location()
    link(loc, {
      [Equation~]
      numbering(
        "1.1",
        counter(heading).at(loc).first(),
        ..counter(math.equation).at(loc),
      )
    })
  } else {
    it
  }
}

= First Chapter
@eq

= Second Chapter
@eq is my equation.
$ a^2 + b^2 = c^2 $ <eq>

= Third Chapter
@eq
== Section
@eq