---
title: math.erfcinv() function
description: math.erfcinv() returns the inverse of math.erfc().
url: https://docs.influxdata.com/flux/v0/stdlib/math/erfcinv/
estimated_tokens: 1605
product: Flux
version: v0
---

# math.erfcinv() function

-   Flux 0.22.0+
-   View InfluxDB support

`math.erfcinv()` returns the inverse of `math.erfc()`.

##### Function type signature

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

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

## Parameters

### x

(Required) Value to operate on.

`x` should be greater than 0 and less than 2. Otherwise the operation will return `NaN`.

## Examples

-   [Return the inverse complimentary error function](#return-the-inverse-complimentary-error-function)
-   [Use math.erfcinv in map](#use-matherfcinv-in-map)

### Return the inverse complimentary error function

```js
import "math"

math.erfcinv(x: 0.42345)// 0.5660037715858239

```

### Use math.erfcinv in map

```js
import "math"

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

[](#view-example-input-and-output)

View example input and output

#### Input data

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 1.9979506490526588 | t1 |
| 2021-01-01T00:00:10Z | 0.000000000000000000000000000000000000000000000000000008381980138107252 | t1 |
| 2021-01-01T00:00:20Z | 0.000000000000000000000000262744434287864 | t1 |
| 2021-01-01T00:00:30Z | 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000011164884065025777 | t1 |
| 2021-01-01T00:00:40Z | 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006790933091004747 | t1 |
| 2021-01-01T00:00:50Z | 0.0000000003729065687554446 | t1 |

| _time | _value | *tag |
| --- | --- | --- |
| 2021-01-01T00:00:00Z | 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002144458719979885 | t2 |
| 2021-01-01T00:00:10Z | 0.0000000000020855419929990413 | t2 |
| 2021-01-01T00:00:20Z | 1.9999998862727435 | t2 |
| 2021-01-01T00:00:30Z | 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005123973574678553 | t2 |
| 2021-01-01T00:00:40Z | 0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000015161509817813512 | t2 |
| 2021-01-01T00:00:50Z | 0.008527511664360422 | 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 | -3.7500000000779927 | t2 |
| 2021-01-01T00:00:30Z | +Inf | t2 |
| 2021-01-01T00:00:40Z | +Inf | t2 |
| 2021-01-01T00:00:50Z | 1.860000000000001 | t2 |