numpy.tanh

numpy.tanh(x[, out])

Compute hyperbolic tangent element-wise.

Equivalent to np.sinh(x)/np.cosh(x) or -1j * np.tan(1j*x).

Parameters :

x : array_like

Input array.

out : ndarray, optional

Output array of same shape as x.

Returns :

y : ndarray

The corresponding hyperbolic tangent values.

Raises :

ValueError: invalid return array shape :

if out is provided and out.shape != x.shape (See Examples)

Notes

If out is provided, the function writes the result into it, and returns a reference to out. (See Examples)

References

[R222]

M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions. New York, NY: Dover, 1972, pg. 83. http://www.math.sfu.ca/~cbm/aands/

[R223]

Wikipedia, “Hyperbolic function”, http://en.wikipedia.org/wiki/Hyperbolic_function

Examples

>>> np.tanh((0, np.pi*1j, np.pi*1j/2))
array([ 0. +0.00000000e+00j,  0. -1.22460635e-16j,  0. +1.63317787e+16j])

>>> # Example of providing the optional output parameter illustrating
>>> # that what is returned is a reference to said parameter
>>> out2 = np.tanh([0.1], out1)
>>> out2 is out1
True

>>> # Example of ValueError due to provision of shape mis-matched `out`
>>> np.tanh(np.zeros((3,3)),np.zeros((2,2)))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid return array shape