# `Expresso.Element.Math.Each`
[🔗](https://github.com/rellen/expresso/blob/main/lib/expresso/element/math/each.ex#L1)

The parts of a formula that name each occurrence of a symbol

A `part` entity with `each: "x"` names each occurrence of `x`. An occurrence
is a token element of the MathML, `mi`, `mn` or `mo`, with the text `x`. The
scope is the part of `within`, or the part with the name of the entity in the
short form, or else the whole formula. With `bare: true`, the base of a
symbol with an index, such as the `x` of `x_1`, is not an occurrence.
`docs/each-occurrence.md` gives the design.

The occurrence `n` of a set also gets the class `set-n`. A copy to a set
thus becomes one copy for each occurrence, and
`Expresso.Element.Math.Links` can take one occurrence as the source of a
link.

# `place`

```elixir
@spec place(Expresso.Element.Math.t()) :: Expresso.Element.Math.t()
```

Give each occurrence of each part with `each` the class of its part

A named set keeps its name, and its occurrences get it as a class. In the
short form, the name of the part is the name of its scope, so the part
takes the name `each-name`, and its occurrences get that class. The
occurrence `n` also gets the class `name-n`.

A copy to a set becomes one copy for each occurrence, with the target
`set-n` and the name `copy-n`. A copy of a set to a set pairs the
occurrences in order.

The function raises for a scope that the formula does not have, for a part
with no occurrence, for a copy of a set to a set with a different number of
occurrences, and for a copy of a copy to a set.

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*Consult [api-reference.md](api-reference.md) for complete listing*