## ASIN

The `ASIN` function in ES|QL returns the arcsine of the input numeric expression as an angle, expressed in radians. This function only accepts numbers between -1 and 1. If the input is null, the function will return null.

### Examples

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

```esql
ROW a=.9
| EVAL asin = ASIN(a)
```

In this example, the `ASIN` function is used to calculate the arcsine of 0.9. The result is stored in the `asin` column.

```esql
ROW a=-.5
| EVAL asin_value = ASIN(a)
```

In this second example, the `ASIN` function is used to calculate the arcsine of -0.5. The result is stored in the `asin_value` column.