BigInteger x2 = x.pow(2);
      // x^2 < 10^(2 * result + 1), or else we would have rounded up
      assertThat(TEN.pow(2 * result + 1)).isGreaterThan(x2);
      // x^2 >= 10^(2 * result - 1), or else we would have rounded down
      assertTrue(result == 0 || TEN.pow(2 * result - 1).compareTo(x2) <= 0);
    }
  }

  @GwtIncompatible // TODO
  public void testLog10HalfDown() {

        .setExpectation(-Math.pow(2, 53), DOWN, CEILING, HALF_DOWN, HALF_EVEN)
        .setExpectation(DoubleUtils.nextDown(-Math.pow(2, 53)), FLOOR, UP, HALF_UP)
        .roundUnnecessaryShouldThrow()
        .test();
  }

  public void testRoundToDouble_negativeTwoToThe54MinusOne() {
    new RoundToDoubleTester(BigDecimal.valueOf((-1L << 54) - 1))

      if (d >= 1.0) {
        assertTrue(log2 >= 0);
        assertTrue(StrictMath.pow(2.0, log2) <= d);
        assertTrue(StrictMath.pow(2.0, log2 + 1) > d);
      } else {
        assertTrue(log2 <= 0);
        assertTrue(StrictMath.pow(2.0, log2) >= d);
        assertTrue(StrictMath.pow(2.0, log2 - 1) < d);
      }
    }
  }

      if (d >= 1.0) {
        assertTrue(log2 >= 0);
        assertTrue(StrictMath.pow(2.0, log2) <= d);
        assertTrue(StrictMath.pow(2.0, log2 + 1) > d);
      } else {
        assertTrue(log2 <= 0);
        assertTrue(StrictMath.pow(2.0, log2) >= d);
        assertTrue(StrictMath.pow(2.0, log2 - 1) < d);
      }
    }
  }

   * Returns {@code b} to the {@code k}th power. Even if the result overflows, it will be equal to
   * {@code BigInteger.valueOf(b).pow(k).longValue()}. This implementation runs in {@code O(log k)}
   * time.
   *
   * @throws IllegalArgumentException if {@code k < 0}
   */
  @GwtIncompatible // TODO
  public static long pow(long b, int k) {
    checkNonNegative("exponent", k);
    if (-2 <= b && b <= 2) {
      switch ((int) b) {

    *   gRPC: Propagate truncated errors (instead of returning gRPC internal
        error).
    *   Augment `parallel_interleave` to support 2 kinds of prefetching.
    *   Improved XLA support for C64-related ops log, pow, atan2, tanh.
    *   Add probabilistic convolutional layers.

## API Changes

*   Introducing `prepare_variance` boolean with default setting to False for
    backward compatibility.