# Source code for mars.tensor.arithmetic.tanh

```
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 1999-2021 Alibaba Group Holding Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import numpy as np
from ... import opcodes as OperandDef
from ..utils import infer_dtype
from .core import TensorUnaryOp
from .utils import arithmetic_operand
@arithmetic_operand(sparse_mode="unary")
class TensorTanh(TensorUnaryOp):
_op_type_ = OperandDef.TANH
_func_name = "tanh"
[docs]@infer_dtype(np.tanh)
def tanh(x, out=None, where=None, **kwargs):
"""
Compute hyperbolic tangent element-wise.
Equivalent to ``mt.sinh(x)/np.cosh(x)`` or ``-1j * mt.tan(1j*x)``.
Parameters
----------
x : array_like
Input tensor.
out : Tensor, None, or tuple of Tensor and None, optional
A location into which the result is stored. If provided, it must have
a shape that the inputs broadcast to. If not provided or `None`,
a freshly-allocated tensor is returned. A tuple (possible only as a
keyword argument) must have length equal to the number of outputs.
where : array_like, optional
Values of True indicate to calculate the ufunc at that position, values
of False indicate to leave the value in the output alone.
**kwargs
Returns
-------
y : Tensor
The corresponding hyperbolic tangent values.
Notes
-----
If `out` is provided, the function writes the result into it,
and returns a reference to `out`. (See Examples)
References
----------
.. [1] M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions.
New York, NY: Dover, 1972, pg. 83.
http://www.math.sfu.ca/~cbm/aands/
.. [2] Wikipedia, "Hyperbolic function",
http://en.wikipedia.org/wiki/Hyperbolic_function
Examples
--------
>>> import mars.tensor as mt
>>> mt.tanh((0, mt.pi*1j, mt.pi*1j/2)).execute()
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
>>> out1 = mt.zeros(1)
>>> out2 = mt.tanh([0.1], out1)
>>> out2 is out1
True
>>> # Example of ValueError due to provision of shape mis-matched `out`
>>> mt.tanh(mt.zeros((3,3)),mt.zeros((2,2)))
Traceback (most recent call last):
...
ValueError: operands could not be broadcast together with shapes (3,3) (2,2)
"""
op = TensorTanh(**kwargs)
return op(x, out=out, where=where)
```