Function to multiply two 7 * 7 matrix
static double [ ] [ ] matrix_product ( double [ ] [ ] a , double [ ] [ ] b ) { double [ ] [ ] c = new double [ 7 ] [ 7 ] ; for ( int i = 0 ; i < 7 ; i ++ ) for ( int j = 0 ; j < 7 ; j ++ ) for ( int k = 0 ; k < 7 ; k ++ ) c [ i ] [ j ] += a [ i ] [ k ] * b [ k ] [ j ] ; return c ; }