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# C Program for printing the lower triangle elements in a matrix

In this section, we are writing a program for printing the lower triangle ( lower diagonal ) elements of a given matrix with order mXn. (m==n) i.e. it should be a square matrix.

For example, if the order of matrix is 3X3.

Then, to do this, we require one input matrix.

For example:

First matrix:

1 2 3

3 4 6

7 8 9

result is : 2 3 6

To write this program, do the following things.

Step 1: read the order of the first matrix

Step 2: read the first matrix

Step 3: write the condition for checking the lower triangle elements and print the result.

Observe the following diagram

assume the given matrix is

1  2 3

4 5 6

7 8 9 if we use the condition

i==j ; we get diagonal elements

i>j ; we get lower diagonal elements

i<j ; we get upper diagonal elements.

```#include <stdio.h>

int main()
{
int  first, result,m, n, i,j;
// read the order of the first matrix.
printf("Enter the number of rows and columns of matrix\n");
scanf("%d%d", &m, &n);

printf("Enter the elements of first matrix\n");
for (i = 0; i < m; i++)
for (j = 0; j < n; j++)
scanf("%d", &first[i][j]);

// if 'i > j' print the lower diagonal element.

for (i = 0; i < m; i++)
{
for (j = 0; j < n; j++)
{
if(i>j)
{
printf("%d \t",first[i][j]);
}
}
}

return 0;
}
```
Program for displaying lower diagonal elements

### Output:

Command Prompt

Enter the number of rows and columns of matrix
3
3
Enter the elements of first matrix
1 2 3
4 5 6
7 8 9

4 7 8

i<j ; we get upper diagonal elements.

use this condition in the above program to get upper diagonal elements.

```#include <stdio.h>

int main()
{
int  first, result,m, n, i,j;
// read the order of the first matrix.
printf("Enter the number of rows and columns of matrix\n");
scanf("%d%d", &m, &n);

printf("Enter the elements of first matrix\n");
for (i = 0; i < m; i++)
for (j = 0; j < n; j++)
scanf("%d", &first[i][j]);

// if 'i < j' print the upper diagonal element.

for (i = 0; i < m; i++)
{
for (j = 0; j < n; j++)
{
if(i<j)
{
printf("%d \t",first[i][j]);
}
}
}

return 0;
}
```
Program for displaying upper diagonal elements

### Output:

Command Prompt

Enter the number of rows and columns of matrix
3
3
Enter the elements of first matrix
1 2 3
4 5 6
7 8 9

2 3 6

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