/**
   * The "base64" base encoding specified by <a
   * href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648 section 4</a>, Base 64 Encoding.
   * (This is the same as the base 64 encoding from <a
   * href="http://tools.ietf.org/html/rfc3548#section-3">RFC 3548</a>.)
   *
   * <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()

  private static final SecretKey SHA512_KEY =
      new SecretKeySpec("secret key".getBytes(UTF_8), "HmacSHA512");

  // From http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Mac
  private static final ImmutableTable<String, SecretKey, HashFunction> ALGORITHMS =
      new ImmutableTable.Builder<String, SecretKey, HashFunction>()
          .put("HmacMD5", MD5_KEY, Hashing.hmacMd5(MD5_KEY))

 *   <li><a target="_parent" href="http://www.cymru.com/Bogons/v6bogon.html">http://www.cymru.com/
 *       Bogons/v6bogon.html</a>
 *   <li><a target="_parent" href="http://www.space.net/~gert/RIPE/ipv6-filters.html">http://www.
 *       space.net/~gert/RIPE/ipv6-filters.html</a>
 * </ul>
 *
 * @author Erik Kline
 * @since 5.0
 */
@J2ktIncompatible
@GwtIncompatible

   * mod(-1, 4) == 3
   * mod(-8, 4) == 0
   * mod(8, 4) == 0
   * }</pre>
   *
   * @throws ArithmeticException if {@code m <= 0}
   * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.17.3">
   *     Remainder Operator</a>
   */
  @GwtIncompatible // TODO
  public static int mod(long x, int m) {
    // Cast is safe because the result is guaranteed in the range [0, m)

    }
  }

  private static int sqrtFloor(int x) {
    // There is no loss of precision in converting an int to a double, according to
    // http://java.sun.com/docs/books/jls/third_edition/html/conversions.html#5.1.2
    return (int) Math.sqrt(x);
  }

  /**
   * Returns the result of dividing {@code p} by {@code q}, rounding using the specified {@code
   * RoundingMode}.
   *

       * throw NoClassDefFoundError thereafter. This is the proper behavior according to the spec.
       * See https://docs.oracle.com/javase/specs/jls/se8/html/jls-12.html#jls-12.4.2 (steps #11 and
       * #5).
       *
       * Note that that "first time" might happen in a test other than
       * testLexicographicalComparatorChoice!
       */
      return false;
    }

  private static final SecretKey SHA512_KEY =
      new SecretKeySpec("secret key".getBytes(UTF_8), "HmacSHA512");

  // From http://docs.oracle.com/javase/7/docs/technotes/guides/security/StandardNames.html#Mac
  private static final ImmutableTable<String, SecretKey, HashFunction> ALGORITHMS =
      new ImmutableTable.Builder<String, SecretKey, HashFunction>()
          .put("HmacMD5", MD5_KEY, Hashing.hmacMd5(MD5_KEY))

   */
  public double sampleCovariance() {
    checkState(count() > 1);
    return sumOfProductsOfDeltas / (count() - 1);
  }

  /**
   * Returns the <a href="http://mathworld.wolfram.com/CorrelationCoefficient.html">Pearson's or
   * product-moment correlation coefficient</a> of the values. The count must greater than one, and
   * the {@code x} and {@code y} values must both have non-zero population variance (i.e. {@code

   *
   * <p>This method is declared to accept any 2 {@code Comparable} objects, even if they are not <a
   * href="https://docs.oracle.com/javase/tutorial/collections/interfaces/order.html">mutually
   * comparable</a>. If you pass objects that are not mutually comparable, this method may throw an
   * exception. (The reason for this decision is lost to time, but the reason <i>might</i> be that

   * {@link java.io.PrintWriter#format PrintWriter.format}, and related methods. These support the
   * full range of <a
   * href="https://docs.oracle.com/javase/9/docs/api/java/util/Formatter.html#syntax">format
   * specifiers</a>, and alert you to usage errors by throwing {@link
   * java.util.IllegalFormatException}.
   *