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);
}

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 ) ; }
construct a vector by appending one vector to another vector .
