Module org.chocosolver
Package org.chocosolver.util.tools

Class MathUtils

  • public final class MathUtils
extends Object
    various mathematics utilities. The functions do not exist in the basic math package Math.*
    Since:
    8 dec. 2008 version 2.0.1
    Version:
    2.0.1
    Author:
    Charles Prud'homme, Arnaud Malapert

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static double ROUNDED_LOG_PRECISION
      Precision for rounded logarithm.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static int combinaison​(int n, int p)
      it computes the number of combinaison C_n^p.
      static int divCeil​(int x, int y)
      Returns the smallest (closest to positive infinity) int value that is greater or equal to a/b.
      static int divFloor​(int x, int y)
      Returns the largest (closest to positive infinity) int value that is less than or equal to a/b.
      static long factorial​(int n)
      simple recursive version of factorial
      static boolean isPowerOfTwo​(int x)  
      static double log​(double value, double exponent)  
      static int max​(int[] values)
      Returns the element with the greatest value in values.
      static int max​(int[][] values)
      Returns the element with the greatest value in values.
      static int min​(int[] values)
      Returns the element with the smallest value in values.
      static int min​(int[][] values)
      Returns the element with the smallest value in values.
      static int pow​(int value, int exp)
      Returns the value of the first argument raised to the power of the second argument.
      static double roundedLog​(double value, double exponent)
      a rounded logarithm to avoid issues with jvm dependant math functions
      static int safeAdd​(int x, int y)
      Returns the sum of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
      static int safeCast​(long x)  
      static int safeMultiply​(int x, int y)
      Returns the product of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
      static int safeSubstract​(int x, int y)
      Returns the difference of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
      static int sum​(int[] values)
      Returns the sum of elements in values.
      static int sum​(int[][] values)
      Retuns the sum of elements in values.
      static int sum​(int[] values, int begin, int end)
      Returns the sum of elements in values from position begin (inclusive) to position end (exclusive).
      static int sumFrom​(int[] values, int begin)
      Returns the sum of elements in values from position begin (inclusive) to values.length.
      static int sumTo​(int[] values, int end)
      Returns the sum of elements in values from position 0 (inclusive) to position end (exclusive).

    • Field Detail

      • ROUNDED_LOG_PRECISION

        public static final double ROUNDED_LOG_PRECISION
        Precision for rounded logarithm.
        See Also:
        Constant Field Values

    • Method Detail

      • factorial

        public static long factorial​(int n)
        simple recursive version of factorial
        Parameters:
        n - size of the suite
        Returns:
        n!

      • combinaison

        public static int combinaison​(int n,
                              int p)
        it computes the number of combinaison C_n^p. The function is only recursive and do not use an array to store temporary results
        Parameters:
        n - max cardinality
        p - sub cardinality
        Returns:
        n among k combinations

      • isPowerOfTwo

        public static boolean isPowerOfTwo​(int x)
        Parameters:
        x - a value
        Returns:
        true if x is power of 2.

      • pow

        public static int pow​(int value,
                      int exp)
        Returns the value of the first argument raised to the power of the second argument. See Math.pow(double, double) for special cases.
        Parameters:
        value -
        exp -
        Returns:

      • log

        public static double log​(double value,
                         double exponent)

      • roundedLog

        public static double roundedLog​(double value,
                                double exponent)
        a rounded logarithm to avoid issues with jvm dependant math functions

      • sum

        public static int sum​(int[] values,
                      int begin,
                      int end)
        Returns the sum of elements in values from position begin (inclusive) to position end (exclusive).
        Parameters:
        values - array of ints
        begin - starting position (inclusive)
        end - ending position (exclusive)
        Returns:
        the sum of elements in values from position begin (inclusive) to position end (exclusive).

      • sumFrom

        public static int sumFrom​(int[] values,
                          int begin)
        Returns the sum of elements in values from position begin (inclusive) to values.length.
        Parameters:
        values - array of ints
        begin - starting position (inclusive)
        Returns:
        the sum of elements in values from position begin (inclusive) to values.length.

      • sumTo

        public static int sumTo​(int[] values,
                        int end)
        Returns the sum of elements in values from position 0 (inclusive) to position end (exclusive).
        Parameters:
        values - array of ints
        end - ending position (exclusive)
        Returns:
        the sum of elements in values from position 0 (inclusive) to position end (exclusive).

      • sum

        public static int sum​(int[] values)
        Returns the sum of elements in values.
        Parameters:
        values - array of ints
        Returns:
        the sum of elements in values.

      • sum

        public static int sum​(int[][] values)
        Retuns the sum of elements in values.
        Parameters:
        values - matrix of ints
        Returns:
        the sum of elements in values.

      • max

        public static int max​(int[] values)
        Returns the element with the greatest value in values.
        Parameters:
        values - array of ints
        Returns:
        the element with the greatest value in values.

      • max

        public static int max​(int[][] values)
        Returns the element with the greatest value in values.
        Parameters:
        values - array of ints
        Returns:
        the element with the greatest value in values.

      • min

        public static int min​(int[] values)
        Returns the element with the smallest value in values.
        Parameters:
        values - array of ints
        Returns:
        the element with the smallest value in values.

      • min

        public static int min​(int[][] values)
        Returns the element with the smallest value in values.
        Parameters:
        values - array of ints
        Returns:
        the element with the smallest value in values.

      • divFloor

        public static int divFloor​(int x,
                           int y)
        Returns the largest (closest to positive infinity) int value that is less than or equal to a/b. Adapted from Math.floorDiv(int, int).
        Parameters:
        x - the dividend
        y - the divisor
        Returns:
        the largest (closest to positive infinity) int value that is less than or equal to a/b.

      • divCeil

        public static int divCeil​(int x,
                          int y)
        Returns the smallest (closest to positive infinity) int value that is greater or equal to a/b. Adapted from Math.floorDiv(int, int).
        Parameters:
        x - the dividend
        y - the divisor
        Returns:
        the smallest (closest to positive infinity) int value that is greater or equal to a/b.

      • safeAdd

        public static int safeAdd​(int x,
                          int y)
        Returns the sum of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
        Parameters:
        x - the first value
        y - the second value
        Returns:
        the result

      • safeSubstract

        public static int safeSubstract​(int x,
                                int y)
        Returns the difference of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
        Parameters:
        x - the first value
        y - the second value
        Returns:
        the result

      • safeMultiply

        public static int safeMultiply​(int x,
                               int y)
        Returns the product of its arguments, returning either Integer.MAX_VALUE if the result overflows an int, or Integer.MIN_VALUE if the result underflows an int, .
        Parameters:
        x - the first value
        y - the second value
        Returns:
        the result

      • safeCast

        public static int safeCast​(long x)
        Parameters:
        x - long to cast
        Returns:
        the closest int value when safe casting a long into an int