# Golang Program to Compute the Sum of Diagonals of a Matrix

In this tutorial, we will write a go language program to find the sum of diagonal elements of a matrix.

## Compute the Sum of Diagonals of a Matrix

In this example, we will find the sum of left diagonal elements of a 3 x 3 matrix using external function.

### Algorithm

Step 1 − Import the fmt package.

Step 2 − Create a function to find the sum of the given matrix.

Step 3 − In this function initialize an integer variable named sum and use a for loop to intend over the matrix array.

Step 4 − In each iteration update the sum variable with the diagonal elements of matrix (like 00, 11, 22) and return the sum variable.

Step 5 − Start the main function. Here, first we need to initialize a matrix and print it on the screen using for loops.

Step 6 − Now, call the matrixSum() by passing the matrix as argument.

Step 7 − Store the result in result variable and print it on the screen using fmt.Println() function.

### Example

package main
import "fmt"

// function to find sum
func matrixSum(mat [][]int, n int) int {
var sum int = 0
for k := range mat {
sum = sum + mat[k][k]
}
return sum
}
func main() {
mat := [][]int{
{10, 1, 2},
{4, 5, 6},
{8, 9, 10},
}
fmt.Println("The given matrix is: \n")
for i := 0; i < 3; i++ {
for j := 0; j < 3; j++ {
fmt.Print(mat[i][j], "\t")
}
fmt.Println()
}
fmt.Println()
var n int = 2
result := matrixSum(mat, n)
fmt.Println("The Sum of left diagonal element of Matrix = ", result)
}


### Output

The given matrix is:

10	1	2
4	5	6
8	9	10

The Sum of left diagonal element of Matrix =  25


## Find the Sum of the Right Diagonal of a 3 x 3 Matrix

In this example, we will write a go language program to find the sum of the right diagonal element of a 3 X 3 matrix.

### Algorithm

Step 1 − Import the fmt package.

Step 2 − Create a function to find the sum of the given matrix.

Step 3 − In this function initialize an integer variable named sum and used a for loops to intend over the matrix array.

Step 4 − In each iteration update the sum variable with the diagonal elements of matrix (like 02, 11, 20) and return the sum variable.

Step 5 − To obtain this we have used a if condition which satisfies the above condition by computing the sum of iterated variables to 2.

Step 6 − Start the main function. Here, first we need to initialize a matrix and print it on the screen using for loops.

Step 7 − Now, call the matrixSum() by passing the matrix as argument.

Step 8 − Store the result in result variable and print it on the screen using fmt.Println() function.

### Example

package main
import "fmt"

// function to find sum
func findSum(mat [][]int, n int) int {
var sum int = 0
for i := 0; i < 3; i++ {
for j := 0; j < 3; j++ {
if i+j == 2 {
sum = sum + mat[i][j]
}
}
}
return sum
}

// calling main()
func main() {
mat := [][]int{
{1, 1, 2},
{4, 5, 6},
{8, 9, 3},
}
fmt.Println("The given matrix is: \n")
for i := 0; i < 3; i++ {
for j := 0; j < 3; j++ {
fmt.Print(mat[i][j], "\t")
}
fmt.Println()
}
fmt.Println()
var n int = 3
result := findSum(mat, n)
fmt.Printf("\nSum of right diagonal elements is: %d", result)
}


### Output

The given matrix is:

1	1	2
4	5	6
8	9	3

Sum of right diagonal elements is: 15


## Conclusion

We have successfully compiled and executed a go language program to find the sum of diagonal elements of a 3 X 3 matrix along with examples. In the first example, we found the sum of left diagonal of a matrix and in the second example, we found the sum of right diagonal of matrix respectively.

Updated on: 28-Dec-2022

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