# xarray.ufuncs.atanh

### xarray.ufuncs.atanh *= <xarray.ufuncs._unary_ufunc object>*

xarray specific variant of `numpy.atanh()`. Handles xarray objects by dispatching to the appropriate function for the underlying array type.

Documentation from numpy:

Inverse hyperbolic tangent, element-wise.

* **Parameters:**
  * **x** ([array_like](https://numpy.org/doc/stable/glossary.html#term-array_like)) – Input array.
  * **out** ([`ndarray`](https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray), [`None`](https://docs.python.org/3/builtins/constants.html#None), or [`tuple`](https://docs.python.org/3/builtins/stdtypes.html#tuple) of [`ndarray`](https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray) and [`None`](https://docs.python.org/3/builtins/constants.html#None), *optional*) – A location into which the result is stored. If provided, it must have
    a shape that the inputs broadcast to. If not provided or None,
    a freshly-allocated array is returned. A tuple (possible only as a
    keyword argument) must have length equal to the number of outputs.
  * **where** ([array_like](https://numpy.org/doc/stable/glossary.html#term-array_like), *optional*) – This condition is broadcast over the input. At locations where the
    condition is True, the out array will be set to the ufunc result.
    Elsewhere, the out array will retain its original value.
    Note that if an uninitialized out array is created via the default
    `out=None`, locations within it where the condition is False will
    remain uninitialized.
  * **\*\*kwargs** – For other keyword-only arguments, see the
    [ufunc docs](https://numpy.org/doc/stable/reference/ufuncs.html#ufuncs-kwargs).
* **Returns:**
  **out** ([`ndarray`](https://numpy.org/doc/stable/reference/generated/numpy.ndarray.html#numpy.ndarray) or [scalar](../user-guide/terminology.html.md#term-scalar)) – Array of the same shape as x.
  This is a scalar if x is a scalar.

#### SEE ALSO
`emath.arctanh`

### Notes

arctanh is a multivalued function: for each x there are infinitely
many numbers z such that `tanh(z) = x`. The convention is to return
the z whose imaginary part lies in [-pi/2, pi/2].

For real-valued input data types, arctanh always returns real output.
For each value that cannot be expressed as a real number or infinity,
it yields `nan` and sets the invalid floating point error flag.

For complex-valued input, arctanh is a complex analytical function
that has branch cuts [-1, -inf] and [1, inf] and is continuous from
above on the former and from below on the latter.

The inverse hyperbolic tangent is also known as atanh or `tanh^-1`.

### References

1. M. Abramowitz and I.A. Stegun, “Handbook of Mathematical Functions”,
   10th printing, 1964, pp. 86.
   [https://personal.math.ubc.ca/~cbm/aands/page_86.htm](https://personal.math.ubc.ca/~cbm/aands/page_86.htm)
2. Wikipedia, “Inverse hyperbolic function”,
   [https://en.wikipedia.org/wiki/Arctanh](https://en.wikipedia.org/wiki/Arctanh)

### Examples

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```pycon
>>> import numpy as np
>>> np.arctanh([0, -0.5])
array([ 0.        , -0.54930614])
```

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