numpy.lib.scimath.arctanh¶

lib.scimath.arctanh(x)[source]

Compute the inverse hyperbolic tangent of x.

Return the “principal value” (for a description of this, see `numpy.arctanh`) of `arctanh(x)`. For real x such that `abs(x) < 1`, this is a real number. If abs(x) > 1, or if x is complex, the result is complex. Finally, x = 1 returns``inf`` and `x=-1` returns `-inf`.

Parameters
xarray_like

The value(s) whose arctanh is (are) required.

Returns
outndarray or scalar

The inverse hyperbolic tangent(s) of the x value(s). If x was a scalar so is out, otherwise an array is returned.

Notes

For an arctanh() that returns `NAN` when real x is not in the interval `(-1,1)`, use `numpy.arctanh` (this latter, however, does return +/-inf for `x = +/-1`).

Examples

```>>> np.set_printoptions(precision=4)
```
```>>> from numpy.testing import suppress_warnings
>>> with suppress_warnings() as sup:
...     sup.filter(RuntimeWarning)
...     np.emath.arctanh(np.eye(2))
array([[inf,  0.],
[ 0., inf]])
>>> np.emath.arctanh([1j])
array([0.+0.7854j])
```