# Source code for mars.tensor.arithmetic.isfinite

```#!/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 inject_dtype
from .core import TensorUnaryOp
from .utils import arithmetic_operand

@arithmetic_operand(sparse_mode="unary")
class TensorIsFinite(TensorUnaryOp):
_op_type_ = OperandDef.ISFINITE
_func_name = "isfinite"

[docs]@inject_dtype(np.bool_)
def isfinite(x, out=None, where=None, **kwargs):
"""
Test element-wise for finiteness (not infinity or not Not a Number).

The result is returned as a boolean tensor.

Parameters
----------
x : array_like
Input values.
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, bool
For scalar input, the result is a new boolean with value True
if the input is finite; otherwise the value is False (input is
either positive infinity, negative infinity or Not a Number).

For array input, the result is a boolean array with the same
dimensions as the input and the values are True if the
corresponding element of the input is finite; otherwise the values
are False (element is either positive infinity, negative infinity
or Not a Number).

--------
isinf, isneginf, isposinf, isnan

Notes
-----
Not a Number, positive infinity and negative infinity are considered
to be non-finite.

Mars uses the IEEE Standard for Binary Floating-Point for Arithmetic
(IEEE 754). This means that Not a Number is not equivalent to infinity.
Also that positive infinity is not equivalent to negative infinity. But
infinity is equivalent to positive infinity.  Errors result if the
second argument is also supplied when `x` is a scalar input, or if
first and second arguments have different shapes.

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

>>> mt.isfinite(1).execute()
True
>>> mt.isfinite(0).execute()
True
>>> mt.isfinite(mt.nan).execute()
False
>>> mt.isfinite(mt.inf).execute()
False
>>> mt.isfinite(mt.NINF).execute()
False
>>> mt.isfinite([mt.log(-1.).execute(),1.,mt.log(0).execute()]).execute()
array([False,  True, False])

>>> x = mt.array([-mt.inf, 0., mt.inf])
>>> y = mt.array([2, 2, 2])
>>> mt.isfinite(x, y).execute()
array([0, 1, 0])
>>> y.execute()
array([0, 1, 0])
"""
op = TensorIsFinite(**kwargs)
return op(x, out=out, where=where)
```