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# numpy.isneginf() in Python

• Last Updated : 23 Oct, 2020

The numpy.isneginf() function tests element-wise whether it is negative infinity or not, and returns the result as a boolean array.
Syntax :

`numpy.isneginf(array, y = None)`

Parameters :

```array : [array_like]Input array or object whose elements, we need to test for infinity.
y     : [array_like]A boolean array with the same shape and type as x to store the result.
```

Return :

```boolean array containing the result. For scalar input, the result is a new boolean with value
True if the input is positive or negative infinity; otherwise the value is False.
For array input, the result is a boolean array with the same shape as the input and the values
are True where the corresponding element of the input is positive or negative infinity;
elsewhere the values are False.
```

Code 1 :

 `# Python Program illustrating``# numpy.isneginf() method``  ` `import` `numpy as geek `` ` `print``(``"Negative : "``, geek.isneginf(``1``), ``"\n"``)`` ` `print``(``"Negative : "``, geek.isneginf(``0``), ``"\n"``)`` ` `# not a number``print``(``"Negative : "``, geek.isneginf(geek.nan), ``"\n"``)`` ` `#  infinity``print``(``"Negative : "``, geek.isneginf(geek.inf), ``"\n"``)`` ` `print``(``"Negative : "``, geek.isneginf(geek.NINF), ``"\n"``) `` ` `x ``=` `geek.array([``-``geek.inf, ``0.``, geek.inf])``y ``=` `geek.array([``2``, ``2``, ``2``])``print``(``"Checking for negativity : "``, geek.isneginf(x, y)) `

Output :

```Negative :  False

Negative :  False

Negative :  False

Negative :  False

Negative :  True

Checking for negativity :  [1 0 0]
```

Code 2 :

 `# Python Program illustrating``# numpy.isneginf() method``   ` `import` `numpy as geek ``  ` `# Returns True/False value for each element ``b ``=` `geek.arange(``18``).reshape(``3``, ``6``)``                ` `print``(``"\n"``,b)``print``(``"\nIs Negative Infifnity : \n"``, geek.isneginf(b))`` ` `# geek.inf  : Positive Infinity``# geek.NINF : negative Infinity``b ``=` `[[geek.inf], ``     ``[geek.NINF]]``print``(``"\nIs Negative Infifnity : \n"``, geek.isneginf(b))`

Output :

```
[[ 0  1  2  3  4  5]
[ 6  7  8  9 10 11]
[12 13 14 15 16 17]]

Is Negative Infifnity :
[[False False False False False False]
[False False False False False False]
[False False False False False False]]

Is Negative Infifnity :
[[False]
[ True]]```

Note :
These codes won’t run on online-ID. Please run them on your systems to explore the working.
.
This article is contributed by Mohit Gupta_OMG 😀. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.