Normalizes the angle between two directions to the acute angle
in between, i.e. angles between 0 and 90\(^\circ\)

## Usage

`deviation_norm(x, y = NULL)`

## Arguments

- x, y
Minuend and subtrahend. Both numeric vectors of angles in degrees.
If `y`

is missing, it treats `x`

as difference. If not, length of subtrahend
`y`

is either `1`

or equal to `length(x)`

.

## Value

numeric vector, acute angles between two directions, i.e. values
between 0 and 90\(^\circ\)

## Examples

```
deviation_norm(175, 5)
#> [1] 10
deviation_norm(c(175, 95, 0), c(5, 85, NA))
#> [1] 10 10 NA
deviation_norm(c(-5, 85, 95, 175, 185, 265, 275, 355, 365))
#> [1] 5 85 85 5 5 85 85 5 5
```