Package com.google.common.math

Class BigIntegerMath

  • @GwtCompatible(emulated=true)
public final class BigIntegerMath
extends java.lang.Object
    A class for arithmetic on values of type BigInteger.

    The implementations of many methods in this class are based on material from Henry S. Warren, Jr.'s Hacker's Delight, (Addison Wesley, 2002).

    Similar functionality for int and for long can be found in IntMath and LongMath respectively.

    Since:
    11.0

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static java.math.BigInteger binomial​(int n, int k)
      Returns n choose k, also known as the binomial coefficient of n and k, that is, n! / (k! (n - k)!).
      static java.math.BigInteger divide​(java.math.BigInteger p, java.math.BigInteger q, java.math.RoundingMode mode)
      Returns the result of dividing p by q, rounding using the specified RoundingMode.
      static java.math.BigInteger factorial​(int n)
      Returns n!, that is, the product of the first n positive integers, or 1 if n == 0.
      static boolean isPowerOfTwo​(java.math.BigInteger x)
      Returns true if x represents a power of two.
      static int log10​(java.math.BigInteger x, java.math.RoundingMode mode)
      Returns the base-10 logarithm of x, rounded according to the specified rounding mode.
      static int log2​(java.math.BigInteger x, java.math.RoundingMode mode)
      Returns the base-2 logarithm of x, rounded according to the specified rounding mode.
      static java.math.BigInteger sqrt​(java.math.BigInteger x, java.math.RoundingMode mode)
      Returns the square root of x, rounded with the specified rounding mode.

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • isPowerOfTwo

        public static boolean isPowerOfTwo​(java.math.BigInteger x)
        Returns true if x represents a power of two.

      • log2

        public static int log2​(java.math.BigInteger x,
                       java.math.RoundingMode mode)
        Returns the base-2 logarithm of x, rounded according to the specified rounding mode.
        Throws:
        java.lang.IllegalArgumentException - if x <= 0
        java.lang.ArithmeticException - if mode is RoundingMode.UNNECESSARY and x is not a power of two

      • log10

        @GwtIncompatible("TODO")
public static int log10​(java.math.BigInteger x,
                        java.math.RoundingMode mode)
        Returns the base-10 logarithm of x, rounded according to the specified rounding mode.
        Throws:
        java.lang.IllegalArgumentException - if x <= 0
        java.lang.ArithmeticException - if mode is RoundingMode.UNNECESSARY and x is not a power of ten

      • sqrt

        @GwtIncompatible("TODO")
public static java.math.BigInteger sqrt​(java.math.BigInteger x,
                                        java.math.RoundingMode mode)
        Returns the square root of x, rounded with the specified rounding mode.
        Throws:
        java.lang.IllegalArgumentException - if x < 0
        java.lang.ArithmeticException - if mode is RoundingMode.UNNECESSARY and sqrt(x) is not an integer

      • divide

        @GwtIncompatible("TODO")
public static java.math.BigInteger divide​(java.math.BigInteger p,
                                          java.math.BigInteger q,
                                          java.math.RoundingMode mode)
        Returns the result of dividing p by q, rounding using the specified RoundingMode.
        Throws:
        java.lang.ArithmeticException - if q == 0, or if mode == UNNECESSARY and a is not an integer multiple of b

      • factorial

        public static java.math.BigInteger factorial​(int n)
        Returns n!, that is, the product of the first n positive integers, or 1 if n == 0.

        Warning: the result takes O(n log n) space, so use cautiously.

        This uses an efficient binary recursive algorithm to compute the factorial with balanced multiplies. It also removes all the 2s from the intermediate products (shifting them back in at the end).

        Throws:
        java.lang.IllegalArgumentException - if n < 0

      • binomial

        public static java.math.BigInteger binomial​(int n,
                                            int k)
        Returns n choose k, also known as the binomial coefficient of n and k, that is, n! / (k! (n - k)!).

        Warning: the result can take as much as O(k log n) space.

        Throws:
        java.lang.IllegalArgumentException - if n < 0, k < 0, or k > n