Class MathUtils

java.lang.Object
tools.jackson.core.io.schubfach.MathUtils
public final class MathUtils extends Object
This class exposes package private utilities for other classes. Thus, all methods are assumed to be invoked with correct arguments, so these are not checked at all.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final long
    A_10
     
    private static final long
    C_10
     
    private static final long
    C_2
     
    private static final long[]
    g
     
    static final int
    H
     
    static final int
    K_MAX
     
    static final int
    K_MIN
     
    private static final long[]
    pow10
     
    private static final int
    Q_10
     
    private static final int
    Q_2
     

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    MathUtils()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static int
    flog10pow2(int e)
    Returns the unique integer k such that 10k ≤ 2e < 10k+1.
    static int
    flog10threeQuartersPow2(int e)
    Returns the unique integer k such that 10k ≤ 3/4 · 2e < 10k+1.
    static int
    flog2pow10(int e)
    Returns the unique integer k such that 2k ≤ 10e < 2k+1.
    static long
    g0(int k)
    Returns g0 as described in g1(int).
    static long
    g1(int k)
    Let 10-k = β 2r, for the unique pair of integer r and real β meeting 2125 ≤ β < 2126.
    (package private) static long
    multiplyHigh(long x, long y)
     
    static long
    pow10(int e)
    Returns 10e.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

  • Constructor Details

    • MathUtils

      private MathUtils()

  • Method Details

    • pow10

      public static long pow10(int e)
      Returns 10e.
      Parameters:
      e - The exponent which must meet 0 ≤ e ≤ H.
      Returns:
      10e.

    • flog10pow2

      public static int flog10pow2(int e)
      Returns the unique integer k such that 10k ≤ 2e < 10k+1.

      The result is correct when |e| ≤ 5_456_721. Otherwise the result is undefined.

      Parameters:
      e - The exponent of 2, which should meet |e| ≤ 5_456_721 for safe results.
      Returns:
      ⌊log102e⌋.

    • flog10threeQuartersPow2

      public static int flog10threeQuartersPow2(int e)
      Returns the unique integer k such that 10k ≤ 3/4 · 2e < 10k+1.

      The result is correct when -2_956_395 ≤ e ≤ 2_500_325. Otherwise the result is undefined.

      Parameters:
      e - The exponent of 2, which should meet -2_956_395 ≤ e ≤ 2_500_325 for safe results.
      Returns:
      ⌊log10(3/4 · 2e)⌋.

    • flog2pow10

      public static int flog2pow10(int e)
      Returns the unique integer k such that 2k ≤ 10e < 2k+1.

      The result is correct when |e| ≤ 1_838_394. Otherwise the result is undefined.

      Parameters:
      e - The exponent of 10, which should meet |e| ≤ 1_838_394 for safe results.
      Returns:
      ⌊log210e⌋.

    • g1

      public static long g1(int k)
      Let 10-k = β 2r, for the unique pair of integer r and real β meeting 2125 ≤ β < 2126. Further, let g = ⌊β⌋ + 1. Split g into the higher 63 bits g1 and the lower 63 bits g0. Thus, g1 = ⌊g 2-63⌋ and g0 = g - g1 263.

      This method returns g1 while g0(int) returns g0.

      If needed, the exponent r can be computed as r = flog2pow10(-k) - 125 (see flog2pow10(int)).

      Parameters:
      k - The exponent of 10, which must meet K_MIN ≤ e ≤ K_MAX.
      Returns:
      g1 as described above.

    • g0

      public static long g0(int k)
      Returns g0 as described in g1(int).
      Parameters:
      k - The exponent of 10, which must meet K_MIN ≤ e ≤ K_MAX.
      Returns:
      g0 as described in g1(int).

    • multiplyHigh

      static long multiplyHigh(long x, long y)