# ASIN

Returns the arcsine of the input numeric expression as an angle, expressed in radians.

## Syntax

`ASIN(number)`

### Parameters

#### `number`

- A number between -1 and 1.  
- If `null`, the function returns `null`.

## Examples

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

Calculate the arcsine of the value `0.9` and return the result in radians.