# scipy.special.erfcinv#

scipy.special.erfcinv(y, out=None) = <ufunc 'erfcinv'>#

Inverse of the complementary error function.

Computes the inverse of the complementary error function.

In the complex domain, there is no unique complex number w satisfying erfc(w)=z. This indicates a true inverse function would be multivalued. When the domain restricts to the real, 0 < x < 2, there is a unique real number satisfying erfc(erfcinv(x)) = erfcinv(erfc(x)).

It is related to inverse of the error function by erfcinv(1-x) = erfinv(x)

Parameters:
yndarray

Argument at which to evaluate. Domain: [0, 2]

outndarray, optional

Optional output array for the function values

Returns:
erfcinvscalar or ndarray

The inverse of erfc of y, element-wise

`erf`

Error function of a complex argument

`erfc`

Complementary error function, `1 - erf(x)`

`erfinv`

Inverse of the error function

Examples

```>>> import numpy as np
>>> import matplotlib.pyplot as plt
>>> from scipy.special import erfcinv
```
```>>> erfcinv(0.5)
0.4769362762044699
```
```>>> y = np.linspace(0.0, 2.0, num=11)
>>> erfcinv(y)
array([        inf,  0.9061938 ,  0.59511608,  0.37080716,  0.17914345,
-0.        , -0.17914345, -0.37080716, -0.59511608, -0.9061938 ,
-inf])
```

Plot the function:

```>>> y = np.linspace(0, 2, 200)
>>> fig, ax = plt.subplots()
>>> ax.plot(y, erfcinv(y))
>>> ax.grid(True)
>>> ax.set_xlabel('y')
>>> ax.set_title('erfcinv(y)')
>>> plt.show()
```