/*
 *  call-seq:
 *     dvector.reject {|x| block }      -> a_dvector
 *  
 *  Returns a new vector containing the items in _dvector_,
 *  except those for which the block is <code>true</code>.
 *     
 *     a = Dvector[ 1, 2, 3, 4 ]
 *     a.reject {|x| x.modulo(2) == 0 }   -> Dvector[1, 3]
 */ 
VALUE dvector_reject(VALUE ary) {