Package org.python.core.util

Class ExtraMath

java.lang.Object
org.python.core.util.ExtraMath
public class ExtraMath extends Object
A static utility class with two additional math functions.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static double
    CLOSE
     
    static double
    EPSILON
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    ExtraMath()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    close(double v, double w)
     
    static boolean
    close(double v, double w, double tol)
    Are v and w "close" to each other?
    static double
    closeFloor(double v)
    Returns floor(v) except when v is very close to the next number, when it returns ceil(v);
    static double
    round(double x, int n)
    Round the argument x to n decimal places.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • EPSILON

      public static double EPSILON

    • CLOSE

      public static double CLOSE

  • Constructor Details

    • ExtraMath

      public ExtraMath()

  • Method Details

    • close

      public static boolean close(double v, double w, double tol)
      Are v and w "close" to each other? Uses a scaled tolerance.

    • close

      public static boolean close(double v, double w)

    • closeFloor

      public static double closeFloor(double v)
      Returns floor(v) except when v is very close to the next number, when it returns ceil(v);

    • round

      public static double round(double x, int n)
      Round the argument x to n decimal places. (Rounding is half-up in Python 2.) The method uses BigDecimal, to compute r(x*10n)*10-n, where r() round to the nearest integer. It takes some short-cuts for extreme values.

      For sufficiently small x*10n, the rounding is to zero, and the return value is a signed zero (same sign as x). Suppose x = a*2b, where the significand we must have a<2. Sufficiently small means such that n log210 < -(b+2).

      For sufficiently large x*10n, the adjustment of rounding is too small to affect the least significant bit. That is a*2b represents an amount greater than one, and rounding no longer affects the value, and the return is x. Since the matissa has 52 fractional bits, sufficiently large means such that n log210 > 52-b.

      Parameters:
      x - to round
      n - decimal places
      Returns:
      x rounded.