question: public ArrayRealVector ( RealVector v1 , ArrayRealVector v2 ) { final int l1 = v1 . getDimension ( ) ; final int l2 = v2 . data . length ; data = new double [ l1 + l2 ] ; for ( int i = 0 ; i < l1 ; ++ i ) { data [ i ] = v1 . getEntry ( i ) ; } System . arraycopy ( v2 . data , 0 , data , l1 , l2 ) ; }
target:  Construct a vector by appending one vector to another vector.