public String toString(){
  StringBuilder s=new StringBuilder();
  for (int i=0; i < d; i++)   s.append(data[i] + " ");
  return s.toString();
}

public String toString ( ) { StringBuilder s = new StringBuilder ( ) ; for ( int i = 0 ; i < d ; i ++ ) s . append ( data [ i ] + " " ) ; return s . toString ( ) ; }
returns a string representation of this vector .
