Class ThetaUtil

java.lang.Object
org.apache.datasketches.thetacommon.ThetaUtil
public final class ThetaUtil extends Object
Utility methods for the Theta Family of sketches
Author:
Lee Rhodes

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_NOMINAL_ENTRIES
    The default nominal entries is provided as a convenience for those cases where the nominal sketch size in number of entries is not provided.
    static final int
    MAX_LG_NOM_LONGS
    The largest Log2 nom entries allowed: 26.
    static final int
    MIN_LG_ARR_LONGS
    The smallest Log2 cache size allowed: 5.
    static final int
    MIN_LG_NOM_LONGS
    The smallest Log2 nom entries allowed: 4.
    static final double
    REBUILD_THRESHOLD
    The hash table rebuild threshold = 15.0/16.0.
    static final double
    RESIZE_THRESHOLD
    The resize threshold = 0.5; tuned for speed.

  • Method Summary

    Modifier and Type
    Method
    Description
    static int
    checkNomLongs(int nomLongs)
    Checks that the given nomLongs is within bounds and returns the Log2 of the ceiling power of 2 of the given nomLongs.
    static int
    startingSubMultiple(int lgTarget, int lgRF, int lgMin)
    Gets the smallest allowed exponent of 2 that it is a sub-multiple of the target by zero, one or more resize factors.

    Methods inherited from class Object

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

  • Field Details

    • MIN_LG_NOM_LONGS

      public static final int MIN_LG_NOM_LONGS
      The smallest Log2 nom entries allowed: 4.
      See Also:

    • MAX_LG_NOM_LONGS

      public static final int MAX_LG_NOM_LONGS
      The largest Log2 nom entries allowed: 26.
      See Also:

    • REBUILD_THRESHOLD

      public static final double REBUILD_THRESHOLD
      The hash table rebuild threshold = 15.0/16.0.
      See Also:

    • RESIZE_THRESHOLD

      public static final double RESIZE_THRESHOLD
      The resize threshold = 0.5; tuned for speed.
      See Also:

    • DEFAULT_NOMINAL_ENTRIES

      public static final int DEFAULT_NOMINAL_ENTRIES
      The default nominal entries is provided as a convenience for those cases where the nominal sketch size in number of entries is not provided. A sketch of 4096 entries has a Relative Standard Error (RSE) of +/- 1.56% at a confidence of 68%; or equivalently, a Relative Error of +/- 3.1% at a confidence of 95.4%. See Default Nominal Entries
      See Also:

    • MIN_LG_ARR_LONGS

      public static final int MIN_LG_ARR_LONGS
      The smallest Log2 cache size allowed: 5.
      See Also:

  • Method Details

    • startingSubMultiple

      public static int startingSubMultiple(int lgTarget, int lgRF, int lgMin)
      Gets the smallest allowed exponent of 2 that it is a sub-multiple of the target by zero, one or more resize factors.
      Parameters:
      lgTarget - Log2 of the target size
      lgRF - Log_base2 of Resize Factor. See Resize Factor
      lgMin - Log2 of the minimum allowed starting size
      Returns:
      The Log2 of the starting size

    • checkNomLongs

      public static int checkNomLongs(int nomLongs)
      Checks that the given nomLongs is within bounds and returns the Log2 of the ceiling power of 2 of the given nomLongs.
      Parameters:
      nomLongs - the given number of nominal longs. This can be any value from 16 to 67108864, inclusive.
      Returns:
      The Log2 of the ceiling power of 2 of the given nomLongs.