arctanh

arctanh(x, out=None, **kwargs)

Inverse hyperbolic tangent, element-wise.

Parameters:
x : ndarray or scalar

Input array.

out : ndarray or None, optional

A location into which the result is stored.
Returns:
arctanh : ndarray

Array of the same shape as x. This is a scalar if x is a scalar.

Notes

arctanh is a multivalued function: for each x there are infinitely many numbers z such that tanh(z) = x.

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.

This function differs from the original numpy.arctanh in the following aspects:
  • Do not support where, a parameter in numpy which indicates where to calculate.
  • Do not support complex-valued input.
  • Cannot cast type automatically. Dtype of out must be same as the expected one.
  • Cannot broadcast automatically. Shape of out must be same as the expected one.
  • If x is plain python numeric, the result won’t be stored in out.

Examples

>>> a = np.array([0.0, -0.5])
>>> np.arctanh(a)
array([0., -0.54930615])

>>> np.arctanh(1)
0.0