## COS

The `COS` function in ES|QL is used to calculate the cosine of an angle. The angle should be provided in radians.

### Examples

Here are a couple of examples of how you can use the `COS` function in ES|QL:

```esql
ROW a=1.8
| EVAL cos = COS(a)
```

In this example, the `COS` function is used to calculate the cosine of the angle `1.8` radians. The result is stored in the `cos` column.

```esql
ROW a=3.14
| EVAL cos_value = COS(a)
```

In this second example, the `COS` function is used to calculate the cosine of the angle `3.14` radians (which is approximately equal to π, the angle for which the cosine is `-1`). The result is stored in the `cos_value` column.