IntMath (Guava Maven Parent 13.0 API)

java.lang.Object
- com.google.common.math.IntMath

```
@Beta
@GwtCompatible(emulated=true)
public final class IntMath
extends Object
```
A class for arithmetic on values of type int. Where possible, methods are defined and named analogously to their BigInteger counterparts.
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 long and for BigInteger can be found in LongMath and BigIntegerMath respectively. For other common operations on int values, see Ints.

Since:

11.0

Author:

Louis Wasserman

Method Summary

Methods
Modifier and Type	Method and Description
`static int`	`binomial(int n, int k)` Returns `n` choose `k`, also known as the binomial coefficient of `n` and `k`, or `Integer.MAX_VALUE` if the result does not fit in an `int`.
`static int`	`checkedAdd(int a, int b)` Returns the sum of `a` and `b`, provided it does not overflow.
`static int`	`checkedMultiply(int a, int b)` Returns the product of `a` and `b`, provided it does not overflow.
`static int`	`checkedPow(int b, int k)` Returns the `b` to the `k`th power, provided it does not overflow.
`static int`	`checkedSubtract(int a, int b)` Returns the difference of `a` and `b`, provided it does not overflow.
`static int`	`divide(int p, int q, RoundingMode mode)` Returns the result of dividing `p` by `q`, rounding using the specified `RoundingMode`.
`static int`	`factorial(int n)` Returns `n!`, that is, the product of the first `n` positive integers, `1` if `n == 0`, or `Integer.MAX_VALUE` if the result does not fit in a `int`.
`static int`	`gcd(int a, int b)` Returns the greatest common divisor of `a, b`.
`static boolean`	`isPowerOfTwo(int x)` Returns `true` if `x` represents a power of two.
`static int`	`log10(int x, RoundingMode mode)` Returns the base-10 logarithm of `x`, rounded according to the specified rounding mode.
`static int`	`log2(int x, RoundingMode mode)` Returns the base-2 logarithm of `x`, rounded according to the specified rounding mode.
`static int`	`mod(int x, int m)` Returns `x mod m`.
`static int`	`pow(int b, int k)` Returns `b` to the `k`th power.
`static int`	`sqrt(int x, RoundingMode mode)` Returns the square root of `x`, rounded with the specified rounding mode.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - isPowerOfTwo
```
public static boolean isPowerOfTwo(int x)
```
    Returns true if x represents a power of two.
    This differs from Integer.bitCount(x) == 1, because Integer.bitCount(Integer.MIN_VALUE) == 1, but Integer.MIN_VALUE is not a power of two.
  - log2
```
public static int log2(int x,
       RoundingMode mode)
```
    Returns the base-2 logarithm of x, rounded according to the specified rounding mode.
    
    Throws:
    
    IllegalArgumentException - if x <= 0
    
    ArithmeticException - if mode is RoundingMode.UNNECESSARY and x is not a power of two
  - log10
```
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int log10(int x,
                             RoundingMode mode)
```
    Returns the base-10 logarithm of x, rounded according to the specified rounding mode.
    
    Throws:
    
    IllegalArgumentException - if x <= 0
    
    ArithmeticException - if mode is RoundingMode.UNNECESSARY and x is not a power of ten
  - pow
```
@GwtIncompatible(value="failing tests")
public static int pow(int b,
                           int k)
```
    Returns b to the kth power. Even if the result overflows, it will be equal to BigInteger.valueOf(b).pow(k).intValue(). This implementation runs in O(log k) time.
    Compare checkedPow(int, int), which throws an ArithmeticException upon overflow.
    
    Throws:
    
    IllegalArgumentException - if k < 0
  - sqrt
```
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int sqrt(int x,
                            RoundingMode mode)
```
    Returns the square root of x, rounded with the specified rounding mode.
    
    Throws:
    
    IllegalArgumentException - if x < 0
    
    ArithmeticException - if mode is RoundingMode.UNNECESSARY and sqrt(x) is not an integer
  - divide
```
public static int divide(int p,
         int q,
         RoundingMode mode)
```
    Returns the result of dividing p by q, rounding using the specified RoundingMode.
    
    Throws:
    
    ArithmeticException - if q == 0, or if mode == UNNECESSARY and a is not an integer multiple of b
  - mod
```
public static int mod(int x,
      int m)
```
    Returns x mod m. This differs from x % m in that it always returns a non-negative result.
    For example:
```
 mod(7, 4) == 3
 mod(-7, 4) == 1
 mod(-1, 4) == 3
 mod(-8, 4) == 0
 mod(8, 4) == 0
```
    Throws:
    
    ArithmeticException - if m <= 0
  - gcd
```
public static int gcd(int a,
      int b)
```
    Returns the greatest common divisor of a, b. Returns 0 if a == 0 && b == 0.
    
    Throws:
    
    IllegalArgumentException - if a < 0 or b < 0
  - checkedAdd
```
public static int checkedAdd(int a,
             int b)
```
    Returns the sum of a and b, provided it does not overflow.
    
    Throws:
    
    ArithmeticException - if a + b overflows in signed int arithmetic
  - checkedSubtract
```
public static int checkedSubtract(int a,
                  int b)
```
    Returns the difference of a and b, provided it does not overflow.
    
    Throws:
    
    ArithmeticException - if a - b overflows in signed int arithmetic
  - checkedMultiply
```
public static int checkedMultiply(int a,
                  int b)
```
    Returns the product of a and b, provided it does not overflow.
    
    Throws:
    
    ArithmeticException - if a * b overflows in signed int arithmetic
  - checkedPow
```
public static int checkedPow(int b,
             int k)
```
    Returns the b to the kth power, provided it does not overflow.
    pow(int, int) may be faster, but does not check for overflow.
    
    Throws:
    
    ArithmeticException - if b to the kth power overflows in signed int arithmetic
  - factorial
```
public static int factorial(int n)
```
    Returns n!, that is, the product of the first n positive integers, 1 if n == 0, or Integer.MAX_VALUE if the result does not fit in a int.
    
    Throws:
    
    IllegalArgumentException - if n < 0
  - binomial
```
@GwtIncompatible(value="need BigIntegerMath to adequately test")
public static int binomial(int n,
                                int k)
```
    Returns n choose k, also known as the binomial coefficient of n and k, or Integer.MAX_VALUE if the result does not fit in an int.
    
    Throws:
    
    IllegalArgumentException - if n < 0, k < 0 or k > n

Class IntMath

Method Summary

Methods inherited from class java.lang.Object

Method Detail

isPowerOfTwo

log2

log10

pow

sqrt

divide

mod

gcd

checkedAdd

checkedSubtract

checkedMultiply

checkedPow

factorial

binomial