---
title: math.erfinv() function
description: >
  `math.erfinv()` returns the inverse error function of `x`.
menu:
  flux_v0_ref:
    name: math.erfinv
    parent: math
    identifier: math/erfinv
weight: 101
---

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`math.erfinv()` returns the inverse error function of `x`.



##### Function type signature

```js
(x: float) => float
```

{{% caption %}}
For more information, see [Function type signatures](/flux/v0/function-type-signatures/).
{{% /caption %}}

## Parameters

### x
({{< req >}})
Value to operate on.

`x` should be greater than -1 and less than 1. Otherwise, the operation will
return `NaN`.


## Examples

- [Return the inverse error function of a value](#return-the-inverse-error-function-of-a-value)
- [Use math.erfinv in map](#use-matherfinv-in-map)

### Return the inverse error function of a value

```js
import "math"

math.erfinv(x: 0.22)// 0.19750838337227364


```


### Use math.erfinv in map

```js
import "math"

data
    |> map(fn: (r) => ({r with _value: math.erfinv(x: r._value)}))

```

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{{% expand "View example input and output" %}}

#### Input data

| _time                | _value              | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | -0.9979506490526588 | t1   |
| 2021-01-01T00:00:10Z | 1                   | t1   |
| 2021-01-01T00:00:20Z | 1                   | t1   |
| 2021-01-01T00:00:30Z | 1                   | t1   |
| 2021-01-01T00:00:40Z | 1                   | t1   |
| 2021-01-01T00:00:50Z | 0.9999999996270934  | t1   |

| _time                | _value              | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | 1                   | t2   |
| 2021-01-01T00:00:10Z | 0.9999999999979144  | t2   |
| 2021-01-01T00:00:20Z | -0.9999998862727434 | t2   |
| 2021-01-01T00:00:30Z | 1                   | t2   |
| 2021-01-01T00:00:40Z | 1                   | t2   |
| 2021-01-01T00:00:50Z | 0.9914724883356396  | t2   |


#### Output data

| _time                | _value              | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | -2.1800000000000006 | t1   |
| 2021-01-01T00:00:10Z | +Inf                | t1   |
| 2021-01-01T00:00:20Z | +Inf                | t1   |
| 2021-01-01T00:00:30Z | +Inf                | t1   |
| 2021-01-01T00:00:40Z | +Inf                | t1   |
| 2021-01-01T00:00:50Z | 4.429999992395194   | t1   |

| _time                | _value              | *tag |
| -------------------- | ------------------- | ---- |
| 2021-01-01T00:00:00Z | +Inf                | t2   |
| 2021-01-01T00:00:10Z | 4.969999434158999   | t2   |
| 2021-01-01T00:00:20Z | -3.7499999999520366 | t2   |
| 2021-01-01T00:00:30Z | +Inf                | t2   |
| 2021-01-01T00:00:40Z | +Inf                | t2   |
| 2021-01-01T00:00:50Z | 1.860000000000001   | t2   |

{{% /expand %}}
{{< /expand-wrapper >}}