# `∘` — Atop

Keys: `Alt-t`

`f∘g Y` is `f(g Y)`, and `X f∘g Y` is `f(X g Y)`.

``` bpl
2 -∘+ 3            ⍝ ¯5
```

See [Rank](rank.qmd) for applying a function to cells of a chosen rank.

## Inverse

`(f∘g)⁻¹Y` is `g⁻¹ f⁻¹ Y`. `X(f∘g)⁻¹Y` is `X g⁻¹ f⁻¹ Y`.

``` bpl
(-∘÷)⁻¹¯0.5   ⍝ 2
```