# numpy.lib.scimath.arctanh

lib.scimath.arctanh(x)

  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
    x array_like

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

  Returns
    out ndarray 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])

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