# Get diagonal of matrix python – Python Program to Find the Sum of all Diagonal Elements of a Matrix

Get diagonal of matrix python: In the previous article, we have discussed Python Program to Check Whether a Matrix is Diagonal or Not

Given a matrix and the task is to find the sum of all diagonal elements of a given matrix in python.

What is a matrix:

Python diagonal matrix: A matrix is a rectangular sequence of numbers divided into columns and rows. A matrix element or entry is a number that appears in a matrix. Matrix diagonal sum in python, diagonal addition of matrix in python, Add diagonal elements matrix in python, Diagonal sum of matrix in python, Get diagonal elements of a matrix python, Python matrix diagonal, Sum of diagonal matrix in python, matrix sum python are all observed here in python diagonal matrix.

Diagonal Matrix:

The entries outside the main diagonal of a diagonal matrix are all 0; the word usually refers to square matrices.

Example:

Above is the matrix which contains 5 rows and 4 columns and having elements from 1 to 20.

In this order, the dimensions of a matrix indicate the number of rows and columns.

Here as there are 5 rows and 4 columns it is called a 5*4 matrix.

Examples:

Example1:

Input:

Given Matrix :
3 0 0
0 1 0
0 0 2

Output:

The Sum of all Diagonal elements of a given Matix =  6

Example2:

Input:

Given Matrix :
1 2 3
6 5 4
7 8 9

Output:

The Sum of all Diagonal elements of a given Matrix = 15

## Program to Find the Sum of all Diagonal Elements of a Matrix in Python

Python get diagonal of matrix: Below are the ways to find the sum of all diagonal elements of a given matrix in python, diagonal matrix python, diagonal sum in python, matrix diagonal sum python applications you can observe here in the program to find the sum of all diagonal elements of a matrix in python. The ways are:

### Method #1: Using For Loop (Static Input)

Approach:

• Give the matrix as static input and store it in a variable.
• Calculate the number of rows of the given matrix by calculating the length of the nested list using the len() function and store it in a variable mtrxrows.
• Calculate the number of columns of the given matrix by calculating the length of the first list in the nested list using the len() function and store it in a variable mtrxcolums.
• Take a variable say diagnl_sum and initialize its value to zero.
• Loop till the given number of rows using the For loop.
• Inside the For loop, Iterate till the given number of columns using another Nested For loop(Inner For loop).
• Check if the condition n is equal to m using the if conditional statement where n is the iterator value of the parent For loop and m is the iterator value of the inner For loop.
• If the statement is true, then add the gvnmatrix[n][m] to the above-initialized diagnl_sum and store it in the same variable diagnl_sum.
• Print the value of diagnl_sum to get the sum of all diagonal elements of a given matrix.
• The Exit of the Program.

Below is the implementation:

# Give the matrix as static input and store it in a variable.
mtrx = [[3, 0, 0], [0, 1, 0], [0, 0, 2]]
# Calculate the number of rows of the given matrix by
# calculating the length of the nested list using the len() function
# and store it in a variable mtrxrows.
mtrxrows = len(mtrx)
# Calculate the number of columns of the given matrix by
# calculating the length of the first list in the nested list
# using the len() function and store it in a variable mtrxcols.
mtrxcols = len(mtrx[0])
# Take a variable say diagnl_sum and initialize its value to zero.
diagnl_sum = 0
# To print all the elements of the given matrix.
# Loop till the given number of rows using the For loop.
for n in range(mtrxrows):
# Inside the For loop, Iterate till the given number of columns using another
# Nested For loop(Inner For loop).
for m in range(mtrxcols):
# Check if the condition n is equal to m using the if conditional statement where n
# is the iterator value of the parent For loop and m is the iterator value of the
# inner For loop.
if n == m:
# If the statement is true, then add the gvnmatrix[n][m] to the above-initialized
# diagnl_sum and store it in the same variable diagnl_sum.
diagnl_sum += mtrx[n][m]
# Print the value of diagnl_sum to get the sum of all diagonal elements of a given matrix.
print("The Sum of all Diagonal elements of a given Matix = ", diagnl_sum)


Output:

The Sum of all Diagonal elements of a given Matix =  6

### Method #2: Using For loop (User Input)

Approach:

• Give the number of rows of the matrix as user input using the int(input()) function and store it in a variable.
• Give the number of columns of the matrix as user input using the int(input()) function and store it in another variable.
• Take a list and initialize it with an empty value using [] or list() to say gvnmatrix.
• Loop till the given number of rows using the For loop
• Inside the For loop, Give all the row elements of the given Matrix as a list using the list(),map(),int(),split() functions and store it in a variable.
• Add the above row elements list to gvnmatrix using the append() function.
• Take a variable say diagnl_sum and initialize its value to zero.
• Loop till the given number of rows using the For loop.
• Inside the For loop, Iterate till the given number of columns using another Nested For loop(Inner For loop).
• Check if the condition n is equal to m using the if conditional statement where n is the iterator value of the parent For loop and m is the iterator value of the inner For loop.
• If the statement is true, then add the gvnmatrix[n][m] to the above-initialized diagnl_sum and store it in the same variable diagnl_sum.
• Print the value of diagnl_sum to get the sum of all diagonal elements of a given matrix.
• The Exit of the Program.

Below is the implementation:

# Give the number of rows of the matrix as user input using the int(input()) function
# and store it in a variable.
mtrxrows = int(input('Enter some random number of rows of the matrix = '))
# Give the number of columns of the matrix as user input using the int(input()) function
# and store it in another variable.
mtrxcols = int(input('Enter some random number of columns of the matrix = '))
# Take a list and initialize it with an empty value using [] or list() to say gvnmatrix.
mtrx = []
# Loop till the given number of rows using the For loop
for n in range(mtrxrows):
# Inside the For loop, Give all the row elements of the given Matrix as a list using
# the list(),map(),int(),split() functions and store it in a variable.
l = list(map(int, input(
'Enter {'+str(mtrxcols)+'} elements of row {'+str(n+1)+'} separated by spaces = ').split()))
# Add the above row elements list to gvnmatrix using the append() function.

mtrx.append(l)

# Take a variable say diagnl_sum and initialize its value to zero.
diagnl_sum = 0
# To print all the elements of the given matrix.
# Loop till the given number of rows using the For loop.
for n in range(mtrxrows):
# Inside the For loop, Iterate till the given number of columns using another
# Nested For loop(Inner For loop).
for m in range(mtrxcols):
# Check if the condition n is equal to m using the if conditional statement where n
# is the iterator value of the parent For loop and m is the iterator value of the
# inner For loop.
if n == m:
# If the statement is true, then add the gvnmatrix[n][m] to the above-initialized
# diagnl_sum and store it in the same variable diagnl_sum.
diagnl_sum += mtrx[n][m]
# Print the value of diagnl_sum to get the sum of all diagonal elements of a given matrix.
print("The Sum of all Diagonal elements of a given Matix = ", diagnl_sum)



Output:

Enter some random number of rows of the matrix = 3
Enter some random number of columns of the matrix = 3
Enter {3} elements of row {1} separated by spaces = 1 2 3
Enter {3} elements of row {2} separated by spaces = 6 5 4
Enter {3} elements of row {3} separated by spaces = 7 8 9
The Sum of all Diagonal elements of a given Matix = 15

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