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

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`math.erfc()` returns the complementary 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.




## Examples

- [Return the complementary error function of a value](#return-the-complementary-error-function-of-a-value)
- [Use math.erfc in map](#use-matherfc-in-map)

### Return the complementary error function of a value

```js
import "math"

math.erfc(x: 22.6)// 3.772618913849058e-224


```


### Use math.erfc in map

```js
import "math"
import "sampledata"

sampledata.float()
    |> map(fn: (r) => ({r with _value: math.erfc(x: r._value)}))

```

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

#### Input data

| _time                | *tag | _value  |
| -------------------- | ---- | ------- |
| 2021-01-01T00:00:00Z | t1   | -2.18   |
| 2021-01-01T00:00:10Z | t1   | 10.92   |
| 2021-01-01T00:00:20Z | t1   | 7.35    |
| 2021-01-01T00:00:30Z | t1   | 17.53   |
| 2021-01-01T00:00:40Z | t1   | 15.23   |
| 2021-01-01T00:00:50Z | t1   | 4.43    |

| _time                | *tag | _value  |
| -------------------- | ---- | ------- |
| 2021-01-01T00:00:00Z | t2   | 19.85   |
| 2021-01-01T00:00:10Z | t2   | 4.97    |
| 2021-01-01T00:00:20Z | t2   | -3.75   |
| 2021-01-01T00:00:30Z | t2   | 19.77   |
| 2021-01-01T00:00:40Z | t2   | 13.86   |
| 2021-01-01T00:00:50Z | t2   | 1.86    |


#### Output 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   |

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