How to horizontally align math symbols by their center when writing a multi-line block?

Questions
, ,
1

Let’s say I have a multi-line block of math: a_1 + a_2 = b on line 1, dots.v on line 2, and y_1 + y_2 = z on line 3. This is the initial code:

$
a_1 + a_2 = b \
dots.v \
y_1 + y_2 = z
$

By default, Typst renders this:

formula
formula288×228 8.4 KB

I would like to align dots.v on line 2 with the center of the equals signs on lines 1 and 3. I tried using alignment points:

$
a_1 + a_2 &= b \
&dots.v \
y_1 + y_2 &= z
$

But that renders like this:

formula(1)
formula(1)290×228 8.16 KB

Even if I wrap the equals signs and ellipses with two alignment points (e.g.: &=& and &dots.v&), it renders the same.

Is there a (preferably easy/quick) way to horizontally align math symbols by their centers, so that vertical ellipses is in line with the center of equals signs, etc.?

2

Hi, welcome to the forum!

Using Matrix Function – Typst Documentation is an option:

$
  mat(
    delim: #none,
    a_1 + a_2, =, b;
    , dots.v;
    y_1 + y_2, =, z;
  )
$

图片
图片414×252 12.2 KB

(If you formula already has ,, replace them with \, when passing to mat.)

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3

Thank you! Would there be a potential downside of using this method with regards to accessibility, such as with screen readers, etc.?

1 Like
4

Is it possible to change the width of the bounding box for dots.v to match the width of the bounding box for =? That way, when using the alignment character &, dots.v and = would align horizontally by their centers.

5

I’ve found out how to do it: use the box function and set the width of the box using measure(math.eq).width.

Like so:

#show math.dots.v: context{
  box(
    width: measure(math.eq).width, 
    math.dots.v
  )
}

This changes the width of dots.v to that of =, but does so for all instances of dots.v which may be undesirable (such as in matrices, because the column width may change).

So as a middle ground, I went with measure($..$) instead; this expands the width of dots.v enough that it is aligned over the = in a system, but only barely increases the width of dots.v in other places like matrices, etc.

Edit: Another method is to use a variable instead of a show rule. That way, you can use it only in the contexts you want. Like this:

#let dveq = context{
  box(
    width: measure(math.eq).width,
    math.dots.v
  )
}

Do either of the above methods compromise accessibility of math equations for screen readers? (I would suspect not in this specific use case)

3 Likes