Module io.jenetics.base
Package io.jenetics.internal.math

Class Basics

java.lang.Object
io.jenetics.internal.math.Basics
public final class Basics extends Object
This object contains mathematical helper functions.
Since:
1.0
Version:
5.2

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    clamp(double v, double lo, double hi)
    Clamping a value between a pair of boundary values.
    static void
    divide(double[] values, double divisor)
    Component wise division of the given double array.
    static boolean
    isMultiplicationSave(int a, int b)
     
    static double[]
    normalize(double[] values)
    Normalize the given double array, so that it sums to one.
    static double[]
    normalize(long[] values)
     
    static long
    pow(long b, long e)
    Binary exponentiation algorithm.
    static long
    ulpDistance(double a, double b)
    Return the ULP distance of the given two double values.
    static long
    ulpPosition(double a)
    Calculating the ULP position of a double number.

    Methods inherited from class java.lang.Object

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

  • Method Details

    • normalize

      public static double[] normalize(double[] values)
      Normalize the given double array, so that it sums to one. The normalization is performed in place and the same values are returned.
      Parameters:
      values - the values to normalize.
      Returns:
      the values array.
      Throws:
      NullPointerException - if the given double array is null.

    • normalize

      public static double[] normalize(long[] values)

    • divide

      public static void divide(double[] values, double divisor)
      Component wise division of the given double array.
      Parameters:
      values - the double values to divide.
      divisor - the divisor.
      Throws:
      NullPointerException - if the given double array is null.

    • pow

      public static long pow(long b, long e)
      Binary exponentiation algorithm.
      Parameters:
      b - the base number.
      e - the exponent.
      Returns:
      b^e.

    • isMultiplicationSave

      public static boolean isMultiplicationSave(int a, int b)

    • clamp

      public static double clamp(double v, double lo, double hi)
      Clamping a value between a pair of boundary values. Note: using clamp with floating point numbers may give unexpected results if one of the values is NaN.
      Parameters:
      v - the value to clamp
      lo - the lower bound.
      hi - the upper bound.
      Returns:
      The clamped value:
      • lo if v < lo
      • hi if hi < v
      • otherwise, v

    • ulpDistance

      public static long ulpDistance(double a, double b)
      Return the ULP distance of the given two double values.
      Parameters:
      a - first double.
      b - second double.
      Returns:
      the ULP distance.
      Throws:
      ArithmeticException - if the distance doesn't fit in a long value.

    • ulpPosition

      public static long ulpPosition(double a)
      Calculating the ULP position of a double number.
      double a = 0.0; for (int i = 0; i < 10; ++i) { a = Math.nextAfter(a, Double.POSITIVE_INFINITY); } for (int i = 0; i < 19; ++i) { a = Math.nextAfter(a, Double.NEGATIVE_INFINITY); System.out.println( a + "\t" + ulpPosition(a) + "\t" + ulpDistance(0.0, a) ); }
      The code fragment above will create the following output: 
         4.4E-323    9  9
   4.0E-323    8  8
   3.5E-323    7  7
   3.0E-323    6  6
   2.5E-323    5  5
   2.0E-323    4  4
   1.5E-323    3  3
   1.0E-323    2  2
   4.9E-324    1  1
   0.0         0  0
  -4.9E-324   -1  1
  -1.0E-323   -2  2
  -1.5E-323   -3  3
  -2.0E-323   -4  4
  -2.5E-323   -5  5
  -3.0E-323   -6  6
  -3.5E-323   -7  7
  -4.0E-323   -8  8
  -4.4E-323   -9  9
      Parameters:
      a - the double number.
      Returns:
      the ULP position.