com.almasb.fxgl.ai.utils

Class ArithmeticUtils

java.lang.Object

com.almasb.fxgl.ai.utils.ArithmeticUtils

public final class ArithmeticUtils
extends Object

Some useful math functions.

Author:

davebaol

Method Summary

Modifier and Type	Method and Description
static int	gcdPositive(int... args) Returns the greatest common divisor of the given absolute values.
static int	gcdPositive(int a, int b) Returns the greatest common divisor of two positive numbers (this precondition is not checked and the result is undefined if not fulfilled) using the "binary gcd" method which avoids division and modulo operations.
static int	lcmPositive(int... args) Returns the least common multiple of the given absolute values.
static int	lcmPositive(int a, int b) Returns the least common multiple of the absolute value of two numbers, using the formula lcm(a, b) = (a / gcd(a, b)) * b.
static int	mulAndCheck(int x, int y) Multiply two integers, checking for overflow.
static float	wrapAngleAroundZero(float a) Wraps the given angle to the range [-PI, PI]

Methods inherited from class java.lang.Object

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

Method Detail

wrapAngleAroundZero

public static float wrapAngleAroundZero(float a)

Wraps the given angle to the range [-PI, PI]

Parameters:

a - the angle in radians

Returns:

the given angle wrapped to the range [-PI, PI]

gcdPositive

public static int gcdPositive(int a,
                              int b)

Returns the greatest common divisor of two positive numbers (this precondition is not checked and the result is undefined if not fulfilled) using the "binary gcd" method which avoids division and modulo operations. See Knuth 4.5.2 algorithm B. The algorithm is due to Josef Stein (1961).

Special cases:

• The result of gcd(x, x), gcd(0, x) and gcd(x, 0) is the value of x.
• The invocation gcd(0, 0) is the only one which returns 0.

Parameters:

a - a non negative number.

b - a non negative number.

Returns:

the greatest common divisor.

lcmPositive

public static int lcmPositive(int a,
                              int b)
                       throws ArithmeticException

Returns the least common multiple of the absolute value of two numbers, using the formula lcm(a, b) = (a / gcd(a, b)) * b.

Special cases:

• The invocations lcm(Integer.MIN_VALUE, n) and lcm(n, Integer.MIN_VALUE), where abs(n) is a power of 2, throw an ArithmeticException, because the result would be 2^31, which is too large for an int value.
• The result of lcm(0, x) and lcm(x, 0) is 0 for any x.

Parameters:

a - a non-negative number.

b - a non-negative number.

Returns:

the least common multiple, never negative.

Throws:

ArithmeticException - if the result cannot be represented as a non-negative int value.

gcdPositive

public static int gcdPositive(int... args)

Returns the greatest common divisor of the given absolute values. This implementation uses gcdPositive(int, int) and has the same special cases.

Parameters:

args - non-negative numbers

Returns:

the greatest common divisor.

lcmPositive

public static int lcmPositive(int... args)

Returns the least common multiple of the given absolute values. This implementation uses lcmPositive(int, int) and has the same special cases.

Parameters:

args - non-negative numbers

Returns:

the least common multiple, never negative.

Throws:

ArithmeticException - if the result cannot be represented as a non-negative int value.

mulAndCheck

public static int mulAndCheck(int x,
                              int y)
                       throws ArithmeticException

Multiply two integers, checking for overflow.

Parameters:

x - first factor

y - second factor

Returns:

the product x * y.

Throws:

ArithmeticException - if the result can not be represented as an int.