Find a function `FUN`

that leads to the following output:

```
curve(FUN, from = -2, to = 2, n = 1000)
grid()
```

**Hint:** aim to keep the answer simple. The main logic of the function can often be summarized in a single line of R code.

##
**Answer: click to reveal**

We can write the function as follows:

```
FUN <- function(x) {
return(abs(x) %% 1)
}
```

This function returns the fractional part of the absolute value of its input. For example:

` FUN(12.345)`

` ## [1] 0.345`

` FUN(-0.1234)`

` ## [1] 0.1234`

`FUN`

can be defined equivalently as:

```
FUN <- function(x) {
return(abs(x) - floor(abs(x)))
}
```

To check that this function is indeed a solution to the puzzle we can redraw the plot:

```
curve(FUN, from = -2, to = 2, n = 1000)
grid()
```

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