Efficiently compute sums of diagonals of a matrix | An efficient PHP program to find sum of diagonals ; Driver Code
< ? php $ MAX = 100 ; function printDiagonalSums ( $ mat , $ n ) { global $ MAX ; $ principal = 0 ; $ secondary = 0 ; for ( $ i = 0 ; $ i < $ n ; $ i ++ ) { $ principal += $ mat [ $ i ] [ $ i ] ; $ secondary += $ mat [ $ i ] [ $ n - $ i - 1 ] ; } echo " Principal ▁ Diagonal : " , $ principal , " STRNEWLINE " ; echo " Secondary ▁ Diagonal : " , $ secondary , " STRNEWLINE " ; } $ a = array ( array ( 1 , 2 , 3 , 4 ) , array ( 5 , 6 , 7 , 8 ) , array ( 1 , 2 , 3 , 4 ) , array ( 5 , 6 , 7 , 8 ) ) ; printDiagonalSums ( $ a , 4 ) ; ? >