# Source code for mars.tensor.arithmetic.sqrt

```#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 1999-2021 Alibaba Group Holding Ltd.
#
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#
# Unless required by applicable law or agreed to in writing, software
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and

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 TensorSqrt(TensorUnaryOp):
_op_type_ = OperandDef.SQRT
_func_name = "sqrt"

[docs]@infer_dtype(np.sqrt)
def sqrt(x, out=None, where=None, **kwargs):
"""
Return the positive square-root of an tensor, element-wise.

Parameters
----------
x : array_like
The values whose square-roots are required.
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
An tensor of the same shape as `x`, containing the positive
square-root of each element in `x`.  If any element in `x` is
complex, a complex tensor is returned (and the square-roots of
negative reals are calculated).  If all of the elements in `x`
are real, so is `y`, with negative elements returning ``nan``.
If `out` was provided, `y` is a reference to it.

Notes
-----
*sqrt* has--consistent with common convention--as its branch cut the
real "interval" [`-inf`, 0), and is continuous from above on it.
A branch cut is a curve in the complex plane across which a given
complex function fails to be continuous.

Examples
--------
>>> import mars.tensor as mt

>>> mt.sqrt([1,4,9]).execute()
array([ 1.,  2.,  3.])

>>> mt.sqrt([4, -1, -3+4J]).execute()
array([ 2.+0.j,  0.+1.j,  1.+2.j])

>>> mt.sqrt([4, -1, mt.inf]).execute()
array([  2.,  NaN,  Inf])
"""
op = TensorSqrt(**kwargs)
return op(x, out=out, where=where)
```