cn.ponfee.disjob.common.util

类 Maths

java.lang.Object

cn.ponfee.disjob.common.util.Maths

public class Maths
extends Object

数学算术 取模：Modulo Operation

作者:

Ponfee

构造器概要

构造器

构造器和说明
Maths()

方法概要

限定符和类型	方法和说明
static int	abs(int n)
static long	abs(long n)
static int	add(int a, int b)
static long	add(long a, long b)
static long	bitsMask(int bits) Returns a long value of bit count mask calculate the bit counts mask long value a: (1 << bits) - 1 b: -1L ^ (-1L << bits) c: ~(-1L << bits) d: Long.MAX_VALUE >>> (63 - bits) bitsMask(0) = 0 : 0000000000000000000000000000000000000000000000000000000000000000 bitsMask(1) = 1 : 0000000000000000000000000000000000000000000000000000000000000001 bitsMask(2) = 3 : 0000000000000000000000000000000000000000000000000000000000000011 bitsMask(10) = 1023 : 0000000000000000000000000000000000000000000000000000001111111111 bitsMask(20) = 1048575 : 0000000000000000000000000000000000000000000011111111111111111111 bitsMask(63) = 9223372036854775807: 0111111111111111111111111111111111111111111111111111111111111111 bitsMask(64) = -1 : 1111111111111111111111111111111111111111111111111111111111111111
static long	ceilDiv(long x, long y)
static long	downDiv(long x, long y)
static int	gcd(int[] array) Returns the greatest common divisor in array
static int	gcd(int a, int b) Returns the greatest common divisor
static double	log(double n, double base) 求以base为底n的对数 Math.log10(double) 求以10为底n的对数（lg） Math.log(double) 以e为底n的对数（自然对数，ln） Math.log1p(double) 以e为底n+1的对数
static double	log2(double n) 以2为底n的对数
static long	pow(long base, int exponent) Returns a long value for baseexponent.
static int	reverseBits(int n) Reverses int number bits 1711380007 = 01100110000000011001011000100111 reverseBits(1711380007) = 11100100011010011000000001100110
static int	rotateLeft(int x, int n) rotate shift left，循环左移位操作：0<=n<=32
static int	subtract(int a, int b)
static long	subtract(long a, long b)
static long	upDiv(long x, long y) upDiv( 7, 3) = 3 upDiv(-7, 3) = -3 upDiv( 7, -3) = -3 upDiv(-7, -3) = 3 upDiv(10, 5) = 2 upDiv( 1, 1) = 1 upDiv(-1, 2) = -1 upDiv( 1, -2) = -1 upDiv( 0, 5) = 0 upDiv( 0, -5) = 0 upDiv( 5, -1) = -5 upDiv(-5, 1) = -5 upDiv( 1, 3) = 1 upDiv(-1, 3) = -1 upDiv( 2, 3) = 1 upDiv(-2, 3) = -1 upDiv(x, y) : 向远于零方向取整 downDiv(x, y) : 向近于零方向取整 ceilDiv(x, y) : 向正无穷方向取整 Math.floorDiv(x, y): 向负无穷方向取整

从类继承的方法 java.lang.Object

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

构造器详细资料

Maths

public Maths()

方法详细资料

log2

public static double log2(double n)

以2为底n的对数

参数:

n - the value

返回:

a value of log(n)/log(2)

log

public static double log(double n,
                         double base)

求以base为底n的对数 Math.log10(double) 求以10为底n的对数（lg） Math.log(double) 以e为底n的对数（自然对数，ln） Math.log1p(double) 以e为底n+1的对数

参数:

n - a value

base - 底数

返回:

a double of logarithm

rotateLeft

public static int rotateLeft(int x,
                             int n)

rotate shift left，循环左移位操作：0<=n<=32

参数:

x - the value

n - shift bit len

返回:

a number of rotate left result

bitsMask

public static long bitsMask(int bits)

 Returns a long value of bit count mask
 calculate the bit counts mask long value
   a: (1 << bits) - 1
   b: -1L ^ (-1L << bits)
   c: ~(-1L << bits)
   d: Long.MAX_VALUE >>> (63 - bits)

  bitsMask(0)  = 0                  : 0000000000000000000000000000000000000000000000000000000000000000
  bitsMask(1)  = 1                  : 0000000000000000000000000000000000000000000000000000000000000001
  bitsMask(2)  = 3                  : 0000000000000000000000000000000000000000000000000000000000000011
  bitsMask(10) = 1023               : 0000000000000000000000000000000000000000000000000000001111111111
  bitsMask(20) = 1048575            : 0000000000000000000000000000000000000000000011111111111111111111
  bitsMask(63) = 9223372036854775807: 0111111111111111111111111111111111111111111111111111111111111111
  bitsMask(64) = -1                 : 1111111111111111111111111111111111111111111111111111111111111111
 

参数:

bits - the bit count

返回:

a long value

reverseBits

public static int reverseBits(int n)

Reverses int number bits 1711380007 = 01100110000000011001011000100111 reverseBits(1711380007) = 11100100011010011000000001100110

参数:

n - the number

返回:

reversed number

pow

public static long pow(long base,
                       int exponent)

Returns a long value for baseexponent.

参数:

base - the base

exponent - the exponent

返回:

a long value for baseexponent.

abs

public static int abs(int n)

abs

public static long abs(long n)

upDiv

public static long upDiv(long x,
                         long y)

 upDiv( 7,  3)  =   3
 upDiv(-7,  3)  =  -3
 upDiv( 7, -3)  =  -3
 upDiv(-7, -3)  =   3
 upDiv(10,  5)  =   2
 upDiv( 1,  1)  =   1
 upDiv(-1,  2)  =  -1
 upDiv( 1, -2)  =  -1
 upDiv( 0,  5)  =   0
 upDiv( 0, -5)  =   0
 upDiv( 5, -1)  =  -5
 upDiv(-5,  1)  =  -5
 upDiv( 1,  3)  =   1
 upDiv(-1,  3)  =  -1
 upDiv( 2,  3)  =   1
 upDiv(-2,  3)  =  -1

 upDiv(x, y)        : 向远于零方向取整
 downDiv(x, y)      : 向近于零方向取整
 ceilDiv(x, y)      : 向正无穷方向取整
 Math.floorDiv(x, y): 向负无穷方向取整
 

参数:

x - the numerator

y - the denominator

返回:

the quotient of up zero

downDiv

public static long downDiv(long x,
                           long y)

ceilDiv

public static long ceilDiv(long x,
                           long y)

add

public static int add(int a,
                      int b)

subtract

public static int subtract(int a,
                           int b)

add

public static long add(long a,
                       long b)

subtract

public static long subtract(long a,
                            long b)

gcd

public static int gcd(int a,
                      int b)

Returns the greatest common divisor

参数:

a - the first number

b - the second number

返回:

gcd

gcd

public static int gcd(int[] array)

Returns the greatest common divisor in array

参数:

array - the int array

返回:

gcd