﻿ NumPy: Compute the sum of the diagonal element of a given array - w3resource # NumPy: Compute the sum of the diagonal element of a given array

## NumPy: Linear Algebra Exercise-15 with Solution

Write a NumPy program to compute the sum of the diagonal element of a given array.

Sample Solution:

Python Code :

``````import numpy as np
m = np.arange(6).reshape(2,3)
print("Original matrix:")
print(m)
result =  np.trace(m)
print("Condition number of the said matrix:")
print(result)
``````

Sample Output:

```Original matrix:
[[0 1 2]
[3 4 5]]
Condition number of the said matrix:
4
```

Python Code Editor:

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## Python: Tips of the Day

Getting the last element of a list:

some_list[-1] is the shortest and most Pythonic.

In fact, you can do much more with this syntax. The some_list[-n] syntax gets the nth-to-last element. So some_list[-1] gets the last element, some_list[-2] gets the second to last, etc, all the way down to some_list[-len(some_list)], which gives you the first element.

You can also set list elements in this way. For instance:

```>>> some_list = [1, 2, 3]
>>> some_list[-1] = 5 # Set the last element
>>> some_list[-2] = 3 # Set the second to last element
>>> some_list
[1, 3, 5]
```

Note that getting a list item by index will raise an IndexError if the expected item doesn't exist. This means that some_list[-1] will raise an exception if some_list is empty, because an empty list can't have a last element.

Ref: https://bit.ly/3d8TfFP