question: public static void swapPivot ( DenseDoubleMatrix2D source , long diag , DenseDoubleMatrix2D s , DenseDoubleMatrix2D t ) { long swapRow = diag ; long swapCol = diag ; double maxValue = Math . abs ( source . getDouble ( diag , diag ) ) ; long rows = source . getRowCount ( ) ; long cols = source . getColumnCount ( ) ; double abs = 0 ; for ( long row = diag ; row < rows ; row ++ ) { for ( long col = diag ; col < cols ; col ++ ) { abs = Math . abs ( source . getDouble ( row , col ) ) ; if ( abs > maxValue ) { maxValue = abs ; swapRow = row ; swapCol = col ; } } } if ( swapRow != diag ) { swapRows ( source , swapRow , diag ) ; swapRows ( t , swapRow , diag ) ; } if ( swapCol != diag ) { swapCols ( source , swapCol , diag ) ; swapCols ( s , swapCol , diag ) ; } }
target:  Swap the matrices so that the largest value is on the pivot