fig10_38.java

Data StructuresAnd Algorithm Analysis In Java Source Code

    public class Fig10_38
    {
/* START: Fig10_38.txt */
        /**
         * Standard matrix multiplication.
         * Arrays start at 0.
         * Assumes a and b are square.
         */
        public static int [ ][ ] multiply( int [ ][ ] a, int [ ][ ] b )
        {
            int n = a.length;
            int [ ][ ] c = new int[ n ][ n ];

            for( int i = 0; i < n; i++ )    // Initialization
                for( int j = 0; j < n; j++ )
                    c[ i ][ j ] = 0;

            for( int i = 0; i < n; i++ )
                for( int j = 0; j < n; j++ )
                    for( int k = 0; k < n; k++ )
                        c[ i ][ j ] += a[ i ][ k ] * b[ k ][ j ];

            return c;
        }
/* END */

        public static void main( String [ ] args )
        {
            int [ ][ ] a = { { 1, 2 }, { 3, 4 } };
            int [ ][ ] c = multiply( a, a );

            System.out.println( c[ 0 ][ 0 ] + " " + c[ 0 ][ 1 ] + " " +
                                c[ 1 ][ 0 ] + " " + c[ 1 ][ 1 ] );
        }
    }