Circular Convolution using Matrix Method | Java program to compute circular convolution of two arrays ; Function to find circular convolution ; Finding the maximum size between the two input sequence sizes ; Copying elements of x to row_vec and padding zeros if size of x < maxSize ; Copying elements of h to col_vec and padding zeros if size of h is less than maxSize ; Generating 2D matrix of circularly shifted elements ; Computing result by matrix multiplication and printing results ; Driver program
class GFG { final static int MAX_SIZE = 10 ; static void convolution ( int [ ] x , int [ ] h , int n , int m ) { int row_vec [ ] = new int [ MAX_SIZE ] ; int col_vec [ ] = new int [ MAX_SIZE ] ; int out [ ] = new int [ MAX_SIZE ] ; int circular_shift_mat [ ] [ ] = new int [ MAX_SIZE ] [ MAX_SIZE ] ; int maxSize = n > m ? n : m ; for ( int i = 0 ; i < maxSize ; i ++ ) { if ( i >= n ) { row_vec [ i ] = 0 ; } else { row_vec [ i ] = x [ i ] ; } } for ( int i = 0 ; i < maxSize ; i ++ ) { if ( i >= m ) { col_vec [ i ] = 0 ; } else { col_vec [ i ] = h [ i ] ; } } int k = 0 , d = 0 ; for ( int i = 0 ; i < maxSize ; i ++ ) { int curIndex = k - d ; for ( int j = 0 ; j < maxSize ; j ++ ) { circular_shift_mat [ j ] [ i ] = row_vec [ curIndex % maxSize ] ; curIndex ++ ; } k = maxSize ; d ++ ; } for ( int i = 0 ; i < maxSize ; i ++ ) { for ( int j = 0 ; j < maxSize ; j ++ ) { out [ i ] += circular_shift_mat [ i ] [ j ] * col_vec [ j ] ; } System . out . print ( out [ i ] + " ▁ " ) ; } } public static void main ( String [ ] args ) { int x [ ] = { 5 , 7 , 3 , 2 } ; int n = x . length ; int h [ ] = { 1 , 5 } ; int m = h . length ; convolution ( x , h , n , m ) ; } }