# Source code for mars.tensor.arithmetic.arcsin

```#!/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 TensorArcsin(TensorUnaryOp):
_op_type_ = OperandDef.ARCSIN
_func_name = "arcsin"

[docs]@infer_dtype(np.arcsin)
def arcsin(x, out=None, where=None, **kwargs):
"""
Inverse sine, element-wise.

Parameters
----------
x : array_like
`y`-coordinate on the unit circle.
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
-------
angle : Tensor
The inverse sine of each element in `x`, in radians and in the
closed interval ``[-pi/2, pi/2]``.  If `x` is a scalar, a scalar
is returned, otherwise a tensor.

--------
sin, cos, arccos, tan, arctan, arctan2, emath.arcsin

Notes
-----
`arcsin` is a multivalued function: for each `x` there are infinitely
many numbers `z` such that :math:`sin(z) = x`.  The convention is to
return the angle `z` whose real part lies in [-pi/2, pi/2].

For real-valued input data types, *arcsin* 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.

For complex-valued input, `arcsin` is a complex analytic function that
has, by convention, the branch cuts [-inf, -1] and [1, inf]  and is
continuous from above on the former and from below on the latter.

The inverse sine is also known as `asin` or sin^{-1}.

References
----------
Abramowitz, M. and Stegun, I. A., *Handbook of Mathematical Functions*,
10th printing, New York: Dover, 1964, pp. 79ff.
http://www.math.sfu.ca/~cbm/aands/

Examples
--------
>>> import mars.tensor as mt
>>> mt.arcsin(1).execute()     # pi/2
1.5707963267948966
>>> mt.arcsin(-1).execute()    # -pi/2
-1.5707963267948966
>>> mt.arcsin(0).execute()
0.0
"""
op = TensorArcsin(**kwargs)
return op(x, out=out, where=where)
```