# Ruby program to calculate the sum of right diagonal the matrix

Ruby Example: Write a program to calculate the sum of right diagonal the matrix.
Submitted by Nidhi, on January 25, 2022

Problem Solution:

In this program, we will create a matrix using the 2D array. Then we read elements of the matrix from the user. After that, we will calculate the sum of the right diagonal matrix and print the result.

Program/Source Code:

The source code to calculate the sum of the right diagonal matrix is given below. The given program is compiled and executed successfully.

```# Ruby program to calculate the sum of
# right diagonal the matrix

TwoDArr = Array.new(3){Array.new(3)}
sum = 0;

printf "Enter elements of MATRIX:\n";
i = 0;
while (i < 3)
j = 0;
while (j < 3)
printf "ELEMENT [%d][%d]: ", i, j;
TwoDArr[i][j] =  gets.chomp.to_i;
j = j + 1;
end
i = i + 1;
end

printf "MATRIX:\n";
i = 0;
while (i < 3)
j = 0;
while (j < 3)
print TwoDArr[i][j]," ";
j = j + 1;
end
i = i + 1;
print "\n";
end

printf("Right diagonal of matrix:\n")
i = 0;
while (i < 3)
j = 0;
while (j < 3)
if ( (i+j) == 2 )
sum = sum + TwoDArr[i][j];
printf "%d ", TwoDArr[i][j];
else
printf(" ");
end
j = j + 1;
end
i = i + 1;
print "\n";
end

printf "Sum of right diagonal of matrix: %d\n",sum;
```

Output:

```Enter elements of MATRIX:
ELEMENT [0][0]: 1
ELEMENT [0][1]: 2
ELEMENT [0][2]: 3
ELEMENT [1][0]: 4
ELEMENT [1][1]: 5
ELEMENT [1][2]: 6
ELEMENT [2][0]: 7
ELEMENT [2][1]: 8
ELEMENT [2][2]: 9
MATRIX:
1 2 3
4 5 6
7 8 9
Right diagonal of matrix:
3
5
7
Sum of right diagonal of matrix: 15
```

Explanation:

In the above program, we created a 3x3 matrix TwoDArr using the 2D array. Then we read the elements of the matrix. After that, we calculated the sum of the right diagonal elements and printed the result.