# numpy.tril() in Python

numpy.tril(a, k=0) : Returns copy of array with lower part of the triangle w.r.t k
Parameters :

```a : input array
k : [int, optional, 0 by default]
Diagonal we require; k>0 means diagonal above main diagonal or vice versa.
```

Returns :

`Lower triangle of a, having same shape and data-type as a.`

 `# Python Programming illustrating ` `# numpy.tril method ` ` `  `import` `numpy as geek ` ` `  `# string input ` `a ``=` `geek.matrix([[``1``, ``21``, ``30``],  ` `                 ``[``63` `,``434``, ``3``],  ` `                 ``[``54``, ``54``, ``56``]]) ` ` `  `print``(``"Main Diagonal elements : \n"``, geek.tril(a), ``"\n"``) ` ` `  `print``(``"Diagonal above main Diagonal elements : \n"``, geek.tril(a, ``1``), ``"\n\n"``) ` ` `  `print``(``"Main Diagonal elements : \n"``, geek.tril(a, ``-``1``)) `

Output :

```Main Diagonal elements :
[[  1   0   0]
[ 63 434   0]
[ 54  54  56]]

Diagonal above main Diagonal elements :
[[  1  21   0]
[ 63 434   3]
[ 54  54  56]]

Main Diagonal elements :
[[ 0  0  0]
[63  0  0]
[54 54  0]]
```

References:
https://docs.scipy.org/doc/numpy/reference/generated/numpy.tril.html#numpy.tril
Note :
These NumPy-Python programs won’t run on onlineID, so run them on your systems to explore them
.
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.