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

<!------------------------------------------------------------------------------

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



##### 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 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)}))

```

{{< expand-wrapper >}}
{{% expand "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   |

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