Given a square matrix and the task is to check the matrix is in lower triangular form or not. A square matrix is called lower triangular if all the entries above the main diagonal are zero.
Examples:
Input : mat[4][4] = {{1, 0, 0, 0}, {1, 4, 0, 0}, {4, 6, 2, 0}, {0, 4, 7, 6}}; Output : Matrix is in lower triangular form. Input : mat[4][4] = {{1, 0, 0, 0}, {4, 3, 0, 1}, {7, 9, 2, 0}, {8, 5, 3, 6}}; Output : Matrix is not in lower triangular form.
PHP
<?php // PHP Program to check lower // triangular matrix. $N = 4; // Function to check matrix is in // lower triangular form or not. function isLowerTriangularMatrix( $mat ) { global $N ; for ( $i = 0; $i < $N ; $i ++) for ( $j = $i + 1; $j < $N ; $j ++) if ( $mat [ $i ][ $j ] != 0) return false; return true; } // Driver Code $mat = array ( array ( 1, 0, 0, 0 ), array ( 1, 4, 0, 0 ), array ( 4, 6, 2, 0 ), array ( 0, 4, 7, 6 )); // Function call if (isLowerTriangularMatrix( $mat )) echo ( "Yes" ); else echo ( "No" ); // This code is contributed by Ajit. ?> |
Output:
Yes
Time Complexity: O(n2), where n represents the number of rows and columns of the given matrix.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
Please refer complete article on Program to check if matrix is lower triangular for more details!
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!