---
title: math.sin
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/math-trig/math-sin
---

```
FLOAT math.sin(FLOAT x)
```

**Available in:** all subroutines

Computes the sine of its argument `x`, measured in radians.

## Parameters

`x` - Floating point value representing an angle in radians.

## Return Value

Upon successful completion, this function returns the sine of `x`.

If `x` is `math.NAN`, a NaN will be returned.

If `x` is ±0, `x` will be returned.

If `x` is `math.POS_INFINITY` or
`math.NEG_INFINITY`, a domain error
occurs and a NaN will be returned.

If `x` is _subnormal_, a range error occurs and `x` will be returned.

## Errors

- If the `x` argument is `math.POS_INFINITY`
  or `math.NEG_INFINITY`, then
  `fastly.error` will be set to `EDOM`.
- If the `x` argument is _subnormal_, then
  `fastly.error` will be set to `ERANGE`.

## Example

```vcl
declare local var.fi FLOAT;
declare local var.fo FLOAT;

set var.fi = math.PI;
set var.fi /= 6;
set var.fo = math.sin(var.fi);
```