Package org.apache.lucene.util

Class MathUtil

  • public final class MathUtil
extends java.lang.Object
    Math static utility methods.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static double acosh​(double a)
      Calculates inverse hyperbolic cosine of a double value.
      static double asinh​(double a)
      Calculates inverse hyperbolic sine of a double value.
      static double atanh​(double a)
      Calculates inverse hyperbolic tangent of a double value.
      static long gcd​(long a, long b)
      Return the greatest common divisor of a and b, consistently with BigInteger.gcd(BigInteger).
      static double log​(double base, double x)
      Calculates logarithm in a given base with doubles.
      static int log​(long x, int base)
      Returns x <= 0 ? 0 : Math.floor(Math.log(x) / Math.log(base))

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • log

        public static int log​(long x,
                      int base)
        Returns x <= 0 ? 0 : Math.floor(Math.log(x) / Math.log(base))
        Parameters:
        base - must be > 1

      • log

        public static double log​(double base,
                         double x)
        Calculates logarithm in a given base with doubles.

      • gcd

        public static long gcd​(long a,
                       long b)
        Return the greatest common divisor of a and b, consistently with BigInteger.gcd(BigInteger).

        NOTE: A greatest common divisor must be positive, but 2^64 cannot be expressed as a long although it is the GCD of Long.MIN_VALUE and 0 and the GCD of Long.MIN_VALUE and Long.MIN_VALUE. So in these 2 cases, and only them, this method will return Long.MIN_VALUE.

      • asinh

        public static double asinh​(double a)
        Calculates inverse hyperbolic sine of a double value.

        Special cases:

        • If the argument is NaN, then the result is NaN.
        • If the argument is zero, then the result is a zero with the same sign as the argument.
        • If the argument is infinite, then the result is infinity with the same sign as the argument.

      • acosh

        public static double acosh​(double a)
        Calculates inverse hyperbolic cosine of a double value.

        Special cases:

        • If the argument is NaN, then the result is NaN.
        • If the argument is +1, then the result is a zero.
        • If the argument is positive infinity, then the result is positive infinity.
        • If the argument is less than 1, then the result is NaN.

      • atanh

        public static double atanh​(double a)
        Calculates inverse hyperbolic tangent of a double value.

        Special cases:

        • If the argument is NaN, then the result is NaN.
        • If the argument is zero, then the result is a zero with the same sign as the argument.
        • If the argument is +1, then the result is positive infinity.
        • If the argument is -1, then the result is negative infinity.
        • If the argument's absolute value is greater than 1, then the result is NaN.