Package com.pnfsoftware.jeb.util.math

Class MathUtil

java.lang.Object

com.pnfsoftware.jeb.util.math.MathUtil

public class MathUtil
extends Object

Set of common operations on Number that are not in Math.

Constructor Summary

Constructors

Constructor	Description
MathUtil()

Method Summary

Modifier and Type	Method	Description
static boolean	almostEquals(double a, double b)	Check for almost equality: tolerate a 1e-7 gap to make up for numerical errors inherent to IEEE754 calculations.
static boolean	almostEquals(double a, double b, double epsilon)	Check for almost equality: tolerate an epsilon gap to make up for numerical errors inherent to IEEE754 calculations.
static double	avg(byte[] array)
static double	avg(char[] array)
static double	avg(double[] array)
static double	avg(float[] array)
static double	avg(int[] array)
static double	avg(long[] array)
static double	avg(short[] array)
static double	avg(Collection<? extends Number> collection)
static boolean	betweenExclusive(long value, long min, long max)	Check that a value is between two bounds (exclusive)
static boolean	betweenInclusive(long value, long min, long max)	Check that a value is between two bounds (inclusive)
static int	bitcount(int value)
static int	bitcount(long value)
static boolean	isPowerOfTwo(int n)	Determine is a strictly positive integer is a power of 2.
static boolean	isPowerOfTwo(long n)	Determine is a strictly positive integer is a power of 2.
static int	log2(int n)	Get the truncated base2 log of the input.
static int	log2(long n)	Get the truncated base2 log of the input.
static long	makeInverseMask(int bitsize)	Create a 64-bit inverse mask.
static long	makeMask(int bitsize)	Create a 64-bit mask.
static long	makeOverflow(int bitsize)	Create a 64-bit overflow.
static int	minPositive(int... values)	Get the min of the values which is > 0.
static int	moduloPositive(int a, int b)	Calculate the positive remainder of two integers.
static int	msb(long value, int bitsize)
static int	pow(int a, int b)	Integer exponentiation.
static long	pow(long a, long b)	Long int exponentiation.
static long	signExtend(long value, int bitsize)
static int	signExtend32(int value, int bitsize)
static long	signExtend32(long value, int bitsize)
static long	unmaskedArithShiftRight(long v, int cnt)
static long	unmaskedShiftLeft(long v, int cnt)
static long	unmaskedShiftRight(long v, int cnt)
static long	zeroExtend(long value, int bitsize)
static long	zeroExtend32(long value, int bitsize)

Methods inherited from class java.lang.Object

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

Constructor Details

MathUtil

public MathUtil()

Method Details

almostEquals

public static boolean almostEquals(double a,
 double b)

Check for almost equality: tolerate a 1e-7 gap to make up for numerical errors inherent to IEEE754 calculations.

Parameters:

a -

b -

Returns:

true if |a-b|<=1e-7

almostEquals

public static boolean almostEquals(double a,
 double b,
 double epsilon)

Check for almost equality: tolerate an epsilon gap to make up for numerical errors inherent to IEEE754 calculations.

Parameters:

a -

b -

epsilon - a positive number

Returns:

true if |a-b|<=epsilon

makeMask

public static long makeMask(int bitsize)

Create a 64-bit mask. Safe replacement for (ONE << BITSIZE) - ONE constructs.

Parameters:

bitsize - bitsize [0, 64]

Returns:

the mask

Throws:

IllegalArgumentException - if the bitsize is OOR

makeInverseMask

public static long makeInverseMask(int bitsize)

Create a 64-bit inverse mask. Safe replacement for ~((ONE << BITSIZE) - ONE) constructs.

Parameters:

bitsize - bitsize [0, 64]

Returns:

the inverse mask

Throws:

IllegalArgumentException - if the bitsize is OOR

makeOverflow

public static long makeOverflow(int bitsize)

Create a 64-bit overflow. Safe replacement for (ONE << BITSIZE) constructs.

Parameters:

bitsize - bitsize [0, 64]

Returns:

the overflow

Throws:

IllegalArgumentException - if the bitsize is OOR

betweenExclusive

public static boolean betweenExclusive(long value,
 long min,
 long max)

Check that a value is between two bounds (exclusive)

Parameters:

value - value

min - min bound

max - max bound

Returns:

true if when value is in range ]min, max[

betweenInclusive

public static boolean betweenInclusive(long value,
 long min,
 long max)

Check that a value is between two bounds (inclusive)

Parameters:

value - value

min - min bound

max - max bound

Returns:

true if when value is in range [min, max]

minPositive

public static int minPositive(int... values)

Get the min of the values which is > 0. (for example when looking for min indexOf)

signExtend32

public static long signExtend32(long value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 32]

Returns:

signExtend32

public static int signExtend32(int value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 32]

Returns:

signExtend

public static long signExtend(long value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 64]

Returns:

zeroExtend32

public static long zeroExtend32(long value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 32]

Returns:

zeroExtend

public static long zeroExtend(long value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 64]

Returns:

msb

public static int msb(long value,
 int bitsize)

Parameters:

value -

bitsize - must be in [0, 64]

Returns:

pow

public static int pow(int a,
 int b)

Integer exponentiation.

Parameters:

a -

b -

Returns:

a**b (may have overflowed)

pow

public static long pow(long a,
 long b)

Long int exponentiation.

Parameters:

a -

b -

Returns:

a**b (may have overflowed)

unmaskedShiftLeft

public static long unmaskedShiftLeft(long v,
 int cnt)

unmaskedShiftRight

public static long unmaskedShiftRight(long v,
 int cnt)

unmaskedArithShiftRight

public static long unmaskedArithShiftRight(long v,
 int cnt)

moduloPositive

public static int moduloPositive(int a,
 int b)

Calculate the positive remainder of two integers.

Note: Java standard modulo operators specifies that the remainder will have the sign of the numerator. This method provides an alternate way to calculate the remainder, often-time more useful, by making sure that it remains positive.

Parameters:

a - any integer

b - a strictly positive integer

Returns:

positive remainder

avg

public static double avg(Collection<? extends Number> collection)

avg

public static double avg(byte[] array)

avg

public static double avg(char[] array)

avg

public static double avg(short[] array)

avg

public static double avg(int[] array)

avg

public static double avg(long[] array)

avg

public static double avg(float[] array)

avg

public static double avg(double[] array)

isPowerOfTwo

public static boolean isPowerOfTwo(int n)

Determine is a strictly positive integer is a power of 2.

Parameters:

n - a positive integer

Returns:

isPowerOfTwo

public static boolean isPowerOfTwo(long n)

Determine is a strictly positive integer is a power of 2.

Parameters:

n - a positive integer

Returns:

log2

public static int log2(int n)

Get the truncated base2 log of the input.

Parameters:

n - must be strictly positive

Returns:

log2

public static int log2(long n)

Get the truncated base2 log of the input.

Parameters:

n - must be strictly positive

Returns:

bitcount

public static int bitcount(int value)

bitcount

public static int bitcount(long value)