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

Ruby Example: Write a program to calculate the sum of left 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 left diagonal matrix and print the result.

Program/Source Code:

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

```# Ruby program to calculate the sum of
# left 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("Left diagonal of matrix:\n")
i = 0;
while (i < 3)
j = 0;
while (j < 3)
if (i == j)
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 left 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
Left diagonal of matrix:
1
5
9
Sum of left 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 left diagonal elements and printed the result.