com.xdev.jadoth.math

Class JaMath

java.lang.Object

com.xdev.jadoth.math.JaMath

public abstract class JaMath
extends Object

Author:

Thomas Muenz

Method Summary

Modifier and Type	Method and Description
static double	avg(double... values)
static float	avg(float... values)
static int	avg(int... values)
static long	avg(long... values)
static BigDecimal	bigDec(double value) Alias for BigDecimal.valueOf(value)
static BigDecimal	bigDec(long value) Alias for BigDecimal.valueOf(value)
static BigInteger	bigInt(int value) Alias for BigInteger.valueOf(value)
static BigInteger	bigInt(long value) Alias for BigInteger.valueOf(value)
static double	cube(double d)
static float	cube(float f)
static int	cube(int i)
static long	cube(long l)
static BigInteger	factorial(BigInteger n)
static int	factorial(int n) Use factorial(long) for n in [0;20]. Use factorial(BigInteger) for any n > 0.
static long	factorial(long n) Use factorial(BigInteger) for any n > 0.
static boolean	isPow2(int value) Determines if the passed value is a power-of-2 value.
static void	line(int x1, int y1, int x2, int y2, IntCoordinateManipulator manipulator)
static Point[]	linePoints(int x1, int y1, int x2, int y2)
static int[]	linePointsInt1D(int x1, int y1, int x2, int y2)
static int[][]	linePointsInt2D(int x1, int y1, int x2, int y2)
static int	log2Bound(int n)
static int	log2pow2(int pow2Value)
static double	max(double... values)
static float	max(float... values)
static int	max(int... values)
static long	max(long... values)
static double	min(double... values)
static float	min(float... values)
static int	min(int... values)
static long	min(long... values)
static double	pow(double base, int exponent)
static float	pow(float base, int exponent)
static int	pow(int base, int exponent) This method is an int version of Math.pow(double, double), using only integer iteration for calculation.
static int	pow2Bound(int n)
static Random	random()
static int	random(int n)
static _intRange	range(int from, int to) Range.
static double	round(double value, int decimals) Normalizes value to the actual closest value for decimals decimals. This is useful if multiple subsequent calulations with double values accumulate rounding errors that drift the value away from the value it actually should (could) be. See the "candy" example in Joshua Bloch's "Effective Java": this method fixes the problem.
static byte[]	sequence(byte from, byte to)
static int[]	sequence(int from, int to) Sequence.
static long[]	sequence(long from, long to)
static short[]	sequence(short from, short to)
static double	square(double d)
static float	square(float f)
static int	square(int i)
static long	square(long l)
static int	stepCountDistance(int x1, int y1, int x2, int y2) Determines the amount of discrete steps from (x1,y1) to (x2,y2), where one step is a change of coordinates in either straight or diagonal direction.
static double	sum(double... values)
static float	sum(float... values)
static int	sum(int... values)
static long	sum(long... values)

Methods inherited from class java.lang.Object

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

Method Detail

pow

public static final int pow(int base,
                            int exponent)
                     throws IllegalArgumentException

This method is an int version of Math.pow(double, double), using only integer iteration for calculation.

As a rule of thumb:
It is faster for exponent < 250 (significantly faster for exponents < 100) and slower for exponent >= 250 (significantly slower for exponents >= 500).
This may depend on the concrete system running the program, of course.
Note that exponent may not be negative, otherwise an IllegalArgumentException is thrown. (Why is there no Math.pow(int, int) in JDK ?)

Parameters:

base -

exponent - my not be negative

Returns:

base^exponent

Throws:

IllegalArgumentException - if exponent is negative

pow2Bound

public static final int pow2Bound(int n)

log2Bound

public static final int log2Bound(int n)

log2pow2

public static final int log2pow2(int pow2Value)

isPow2

public static final boolean isPow2(int value)

Determines if the passed value is a power-of-2 value.

Parameters:

value -

Returns:

true for any n in [1;30] that fulfills value = 2^n

pow

public static final float pow(float base,
                              int exponent)
                       throws IllegalArgumentException

Throws:

IllegalArgumentException

pow

public static final double pow(double base,
                               int exponent)
                        throws IllegalArgumentException

Throws:

IllegalArgumentException

square

public static final float square(float f)

square

public static final long square(long l)

square

public static final int square(int i)

square

public static final double square(double d)

cube

public static final float cube(float f)

cube

public static final long cube(long l)

cube

public static final int cube(int i)

cube

public static final double cube(double d)

round

public static final double round(double value,
                                 int decimals)

Normalizes value to the actual closest value for decimals decimals.
This is useful if multiple subsequent calulations with double values accumulate rounding errors that drift the value away from the value it actually should (could) be.
See the "candy" example in Joshua Bloch's "Effective Java": this method fixes the problem.

Note that decimals may not be negative.
And note that while a value of 0 for decimals will yield the correct result, it makes not much sense to call this method for it in the first place.

Parameters:

value - any double value

decimals - the number of decimals. May not be negative.

Returns:

the normalized value for value

range

public static _intRange range(int from,
                              int to)

Range.

Parameters:

from - the from

to - the to

Returns:

the range

sequence

public static byte[] sequence(byte from,
                              byte to)

sequence

public static short[] sequence(short from,
                               short to)

sequence

public static int[] sequence(int from,
                             int to)

Sequence.

Parameters:

from - the from

to - the to

Returns:

the int[]

sequence

public static long[] sequence(long from,
                              long to)
                       throws IllegalArgumentException

Parameters:

from -

to -

Returns:

Throws:

IllegalArgumentException - if the range [from;to] is greater than Integer.MAX_VALUE

max

public static final double max(double... values)

max

public static final float max(float... values)

max

public static final int max(int... values)

max

public static final long max(long... values)

min

public static final double min(double... values)

min

public static final float min(float... values)

min

public static final int min(int... values)

min

public static final long min(long... values)

sum

public static final double sum(double... values)

sum

public static final float sum(float... values)

sum

public static final int sum(int... values)

sum

public static final long sum(long... values)

avg

public static final double avg(double... values)

avg

public static final float avg(float... values)

avg

public static final int avg(int... values)

avg

public static final long avg(long... values)

stepCountDistance

public static final int stepCountDistance(int x1,
                                          int y1,
                                          int x2,
                                          int y2)

Determines the amount of discrete steps from (x1,y1) to (x2,y2), where one step is a change of coordinates in either straight or diagonal direction.

Examples:
(0,0) to (2,0) = 2 steps
(0,0) to (2,2) = 2 steps
(5,18) to (10,9) = 9 steps

Parameters:

x1 -

y1 -

x2 -

y2 -

Returns:

linePoints

public static final Point[] linePoints(int x1,
                                       int y1,
                                       int x2,
                                       int y2)

linePointsInt1D

public static final int[] linePointsInt1D(int x1,
                                          int y1,
                                          int x2,
                                          int y2)

linePointsInt2D

public static final int[][] linePointsInt2D(int x1,
                                            int y1,
                                            int x2,
                                            int y2)

line

public static final void line(int x1,
                              int y1,
                              int x2,
                              int y2,
                              IntCoordinateManipulator manipulator)
                       throws InvalidCoordinateException

Throws:

InvalidCoordinateException

factorial

public static final int factorial(int n)
                           throws IllegalArgumentException

Use factorial(long) for n in [0;20].
Use factorial(BigInteger) for any n > 0.

Parameters:

n - natural number in [0;12]

Returns:

n!

Throws:

IllegalArgumentException - for n < 0 or n > 12

factorial

public static final long factorial(long n)
                            throws IllegalArgumentException

Use factorial(BigInteger) for any n > 0.

Parameters:

n - natural number in [0;20]

Returns:

n!

Throws:

IllegalArgumentException - for n < 0 or n > 20

factorial

public static final BigInteger factorial(BigInteger n)
                                  throws IllegalArgumentException

Parameters:

n - any natural number >= 0

Returns:

n!

Throws:

IllegalArgumentException - for n < 0

bigInt

public static final BigInteger bigInt(int value)

Alias for BigInteger.valueOf(value)

Parameters:

value - any value

Returns:

a BigInteger representing value

bigInt

public static final BigInteger bigInt(long value)

Alias for BigInteger.valueOf(value)

Parameters:

value - any value

Returns:

a BigInteger representing value

bigDec

public static final BigDecimal bigDec(long value)

Alias for BigDecimal.valueOf(value)

Parameters:

value - any value

Returns:

a BigDecimal representing value

bigDec

public static final BigDecimal bigDec(double value)

Alias for BigDecimal.valueOf(value)

Parameters:

value - any value

Returns:

a BigDecimal representing value

random

public static final Random random()

Returns:

the random

random

public static final int random(int n)