code: public boolean compareAndSet(int i, double expected, double update)
      {
          long expectedL = Double.doubleToRawLongBits(expected);
          long updateL = Double.doubleToRawLongBits(update);
          return larray.compareAndSet(i, expectedL, updateL);
      }
docs: Atomically sets the element at position {@code i} to the given
  updated value if the current value {@code ==} the expected value.
  
  @param i the index
  @param expected the expected value
  @param update the new value
  @return true if successful. False return indicates that
  the actual value was not equal to the expected value.