Now comput B * r for evaluating expression A * ( B * r ) - ( C * r )
int br [ ] = new int [ N ] ; Arrays . fill ( br , 0 ) ; for ( int i = 0 ; i < N ; i ++ ) for ( int j = 0 ; j < N ; j ++ ) br [ i ] = br [ i ] + b [ i ] [ j ] * r [ j ] ;