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.

See also

numpy.arctanh

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])