## org.apache.commons.math.util
Class MathUtils

    java.lang.Object
      org.apache.commons.math.util.MathUtils

    public final class MathUtils

extends java.lang.Object

Some useful additions to the built-in functions in `Math`.

Version:
  $Revision: 927249 $ $Date: 2010-03-24 21:06:51 -0400 (Wed, 24 Mar 2010) $

Field Summary
`static double` `EPSILON` Smallest positive number such that 1 - EPSILON is not numerically equal to 1.
`private static long[]` `FACTORIALS` All long-representable factorials
`private static int` `NAN_GAP` Gap between NaN and regular numbers.
`private static byte` `NB` -1.0 cast as a byte.
`private static short` `NS` -1.0 cast as a short.
`private static byte` `PB` 1.0 cast as a byte.
`private static short` `PS` 1.0 cast as a short.
`static double` `SAFE_MIN` Safe minimum, such that 1 / SAFE_MIN does not overflow.
`private static long` `SGN_MASK` Offset to order signed double numbers lexicographically.
`static double` `TWO_PI` 2 π.
`private static byte` `ZB` 0.0 cast as a byte.
`private static short` `ZS` 0.0 cast as a short.

Constructor Summary
`private` `MathUtils()` Private Constructor

Method Summary
`static int` `addAndCheck(int x, int y)` Add two integers, checking for overflow.
`static long` `addAndCheck(long a, long b)` Add two long integers, checking for overflow.
`private static long` `addAndCheck(long a, long b, java.lang.String msg)` Add two long integers, checking for overflow.
`static long` `binomialCoefficient(int n, int k)` Returns an exact representation of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.
`static double` `binomialCoefficientDouble(int n, int k)` Returns a `double` representation of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.
`static double` `binomialCoefficientLog(int n, int k)` Returns the natural `log` of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.
`private static void` `checkBinomial(int n, int k)` Check binomial preconditions.
`static void` `checkOrder(double[] val, int dir, boolean strict)` Checks that the given array is sorted.
`static int` `compareTo(double x, double y, double eps)` Compares two numbers given some amount of allowed error.
`static double` `cosh(double x)` Returns the hyperbolic cosine of x.
`static double` `distance(double[] p1, double[] p2)` Calculates the L2 (Euclidean) distance between two points.
`static double` `distance(int[] p1, int[] p2)` Calculates the L2 (Euclidean) distance between two points.
`static double` `distance1(double[] p1, double[] p2)` Calculates the L1 (sum of abs) distance between two points.
`static int` `distance1(int[] p1, int[] p2)` Calculates the L1 (sum of abs) distance between two points.
`static double` `distanceInf(double[] p1, double[] p2)` Calculates the L∞ (max of abs) distance between two points.
`static int` `distanceInf(int[] p1, int[] p2)` Calculates the L∞ (max of abs) distance between two points.
`static boolean` `equals(double[] x, double[] y)` Returns true iff both arguments are null or have same dimensions and all their elements are `equals`
`static boolean` `equals(double x, double y)` Returns true iff both arguments are NaN or neither is NaN and they are equal
`static boolean` `equals(double x, double y, double eps)` Returns true iff both arguments are equal or within the range of allowed error (inclusive).
`static boolean` `equals(double x, double y, int maxUlps)` Returns true iff both arguments are equal or within the range of allowed error (inclusive).
`static long` `factorial(int n)` Returns n!.
`static double` `factorialDouble(int n)` Returns n!.
`static double` `factorialLog(int n)` Returns the natural logarithm of n!.
`static int` `gcd(int p, int q)` Gets the greatest common divisor of the absolute value of two numbers, using the "binary gcd" method which avoids division and modulo operations.
`static long` `gcd(long p, long q)` Gets the greatest common divisor of the absolute value of two numbers, using the "binary gcd" method which avoids division and modulo operations.
`static int` `hash(double value)` Returns an integer hash code representing the given double value.
`static int` `hash(double[] value)` Returns an integer hash code representing the given double array.
`static byte` `indicator(byte x)` For a byte value x, this method returns (byte)(+1) if x >= 0 and (byte)(-1) if x < 0.
`static double` `indicator(double x)` For a double precision value x, this method returns +1.0 if x >= 0 and -1.0 if x < 0.
`static float` `indicator(float x)` For a float value x, this method returns +1.0F if x >= 0 and -1.0F if x < 0.
`static int` `indicator(int x)` For an int value x, this method returns +1 if x >= 0 and -1 if x < 0.
`static long` `indicator(long x)` For a long value x, this method returns +1L if x >= 0 and -1L if x < 0.
`static short` `indicator(short x)` For a short value x, this method returns (short)(+1) if x >= 0 and (short)(-1) if x < 0.
`static int` `lcm(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 long` `lcm(long a, long 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 double` `log(double base, double x)` Returns the logarithm for base `b` of `x`.
`static int` `mulAndCheck(int x, int y)` Multiply two integers, checking for overflow.
`static long` `mulAndCheck(long a, long b)` Multiply two long integers, checking for overflow.
`static double` `nextAfter(double d, double direction)` Get the next machine representable number after a number, moving in the direction of another number.
`static double` `normalizeAngle(double a, double center)` Normalize an angle in a 2&pi wide interval around a center value.
`static double[]` `normalizeArray(double[] values, double normalizedSum)` Normalizes an array to make it sum to a specified value.
`static java.math.BigInteger` `pow(java.math.BigInteger k, java.math.BigInteger e)` Raise a BigInteger to a BigInteger power.
`static java.math.BigInteger` `pow(java.math.BigInteger k, int e)` Raise a BigInteger to an int power.
`static java.math.BigInteger` `pow(java.math.BigInteger k, long e)` Raise a BigInteger to a long power.
`static int` `pow(int k, int e)` Raise an int to an int power.
`static int` `pow(int k, long e)` Raise an int to a long power.
`static long` `pow(long k, int e)` Raise a long to an int power.
`static long` `pow(long k, long e)` Raise a long to a long power.
`static double` `round(double x, int scale)` Round the given value to the specified number of decimal places.
`static double` `round(double x, int scale, int roundingMethod)` Round the given value to the specified number of decimal places.
`static float` `round(float x, int scale)` Round the given value to the specified number of decimal places.
`static float` `round(float x, int scale, int roundingMethod)` Round the given value to the specified number of decimal places.
`private static double` `roundUnscaled(double unscaled, double sign, int roundingMethod)` Round the given non-negative, value to the "nearest" integer.
`static double` `scalb(double d, int scaleFactor)` Scale a number by 2scaleFactor.
`static byte` `sign(byte x)` Returns the sign for byte value `x`.
`static double` `sign(double x)` Returns the sign for double precision `x`.
`static float` `sign(float x)` Returns the sign for float value `x`.
`static int` `sign(int x)` Returns the sign for int value `x`.
`static long` `sign(long x)` Returns the sign for long value `x`.
`static short` `sign(short x)` Returns the sign for short value `x`.
`static double` `sinh(double x)` Returns the hyperbolic sine of x.
`static int` `subAndCheck(int x, int y)` Subtract two integers, checking for overflow.
`static long` `subAndCheck(long a, long b)` Subtract two long integers, checking for overflow.

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

Field Detail

### EPSILON

    public static final double EPSILON

  Smallest positive number such that 1 - EPSILON is not numerically equal to 1.

  See Also:
    Constant Field Values

### SAFE_MIN

    public static final double SAFE_MIN

  Safe minimum, such that 1 / SAFE_MIN does not overflow.

  In IEEE 754 arithmetic, this is also the smallest normalized number 2-1022.

  See Also:
    Constant Field Values

### TWO_PI

    public static final double TWO_PI

  2 π.

  Since:
    2.1
  See Also:
    Constant Field Values

### NB

    private static final byte NB

  -1.0 cast as a byte.

  See Also:
    Constant Field Values

### NS

    private static final short NS

  -1.0 cast as a short.

  See Also:
    Constant Field Values

### PB

    private static final byte PB

  1.0 cast as a byte.

  See Also:
    Constant Field Values

### PS

    private static final short PS

  1.0 cast as a short.

  See Also:
    Constant Field Values

### ZB

    private static final byte ZB

  0.0 cast as a byte.

  See Also:
    Constant Field Values

### ZS

    private static final short ZS

  0.0 cast as a short.

  See Also:
    Constant Field Values

### NAN_GAP

    private static final int NAN_GAP

  Gap between NaN and regular numbers.

  See Also:
    Constant Field Values

### SGN_MASK

    private static final long SGN_MASK

  Offset to order signed double numbers lexicographically.

  See Also:
    Constant Field Values

### FACTORIALS

    private static final long[] FACTORIALS

  All long-representable factorials

Constructor Detail

### MathUtils

    private MathUtils()

  Private Constructor

Method Detail

### addAndCheck

    public static int addAndCheck(int x,
                                  int y)

  Add two integers, checking for overflow.

  Parameters:
    `x` - an addend
    `y` - an addend
  Returns:
    the sum `x+y`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an int
  Since:
    1.1

### addAndCheck

    public static long addAndCheck(long a,
                                   long b)

  Add two long integers, checking for overflow.

  Parameters:
    `a` - an addend
    `b` - an addend
  Returns:
    the sum `a+b`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an long
  Since:
    1.2

### addAndCheck

    private static long addAndCheck(long a,
                                    long b,
                                    java.lang.String msg)

  Add two long integers, checking for overflow.

  Parameters:
    `a` - an addend
    `b` - an addend
    `msg` - the message to use for any thrown exception.
  Returns:
    the sum `a+b`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an long
  Since:
    1.2

### binomialCoefficient

    public static long binomialCoefficient(int n,
                                           int k)

  Returns an exact representation of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.

  Preconditions:

  - `0 <= k <= n` (otherwise `IllegalArgumentException` is thrown)
  - The result is small enough to fit into a `long`. The largest value of `n` for which all coefficients are `< Long.MAX_VALUE` is 66. If the computed value exceeds `Long.MAX_VALUE` an `ArithMeticException` is thrown.

  Parameters:
    `n` - the size of the set
    `k` - the size of the subsets to be counted
  Returns:
    `n choose k`
  Throws:
    `java.lang.IllegalArgumentException` - if preconditions are not met.
    `java.lang.ArithmeticException` - if the result is too large to be represented by a long integer.

### binomialCoefficientDouble

    public static double binomialCoefficientDouble(int n,
                                                   int k)

  Returns a `double` representation of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.

  Preconditions:

  - `0 <= k <= n` (otherwise `IllegalArgumentException` is thrown)
  - The result is small enough to fit into a `double`. The largest value of `n` for which all coefficients are < Double.MAX_VALUE is 1029. If the computed value exceeds Double.MAX_VALUE, Double.POSITIVE_INFINITY is returned

  Parameters:
    `n` - the size of the set
    `k` - the size of the subsets to be counted
  Returns:
    `n choose k`
  Throws:
    `java.lang.IllegalArgumentException` - if preconditions are not met.

### binomialCoefficientLog

    public static double binomialCoefficientLog(int n,
                                                int k)

  Returns the natural `log` of the Binomial Coefficient, "`n choose k`", the number of `k`-element subsets that can be selected from an `n`-element set.

  Preconditions:

  - `0 <= k <= n` (otherwise `IllegalArgumentException` is thrown)

  Parameters:
    `n` - the size of the set
    `k` - the size of the subsets to be counted
  Returns:
    `n choose k`
  Throws:
    `java.lang.IllegalArgumentException` - if preconditions are not met.

### checkBinomial

    private static void checkBinomial(int n,
                                      int k)
                               throws java.lang.IllegalArgumentException

  Check binomial preconditions.

  Parameters:
    `n` - the size of the set
    `k` - the size of the subsets to be counted
  Throws:
    `java.lang.IllegalArgumentException` - if preconditions are not met.

### compareTo

    public static int compareTo(double x,
                                double y,
                                double eps)

  Compares two numbers given some amount of allowed error.

  Parameters:
    `x` - the first number
    `y` - the second number
    `eps` - the amount of error to allow when checking for equality
  Returns:
    - 0 if `equals(x, y, eps)`
    - < 0 if !`equals(x, y, eps)` && x < y
    - > 0 if !`equals(x, y, eps)` && x > y

### cosh

    public static double cosh(double x)

  Returns the hyperbolic cosine of x.

  Parameters:
    `x` - double value for which to find the hyperbolic cosine
  Returns:
    hyperbolic cosine of x

### equals

    public static boolean equals(double x,
                                 double y)

  Returns true iff both arguments are NaN or neither is NaN and they are equal

  Parameters:
    `x` - first value
    `y` - second value
  Returns:
    true if the values are equal or both are NaN

### equals

    public static boolean equals(double x,
                                 double y,
                                 double eps)

  Returns true iff both arguments are equal or within the range of allowed error (inclusive).

  Two NaNs are considered equals, as are two infinities with same sign.

  Parameters:
    `x` - first value
    `y` - second value
    `eps` - the amount of absolute error to allow
  Returns:
    true if the values are equal or within range of each other

### equals

    public static boolean equals(double x,
                                 double y,
                                 int maxUlps)

  Returns true iff both arguments are equal or within the range of allowed error (inclusive). Adapted from Bruce Dawson

  Parameters:
    `x` - first value
    `y` - second value
    `maxUlps` - `(maxUlps - 1)` is the number of floating point values between `x` and `y`.
  Returns:
    `true` if there are less than `maxUlps` floating point values between `x` and `y`

### equals

    public static boolean equals(double[] x,
                                 double[] y)

  Returns true iff both arguments are null or have same dimensions and all their elements are `equals`

  Parameters:
    `x` - first array
    `y` - second array
  Returns:
    true if the values are both null or have same dimension and equal elements
  Since:
    1.2

### factorial

    public static long factorial(int n)

  Returns n!. Shorthand for `n` Factorial, the product of the numbers `1,...,n`.

  Preconditions:

  - `n >= 0` (otherwise `IllegalArgumentException` is thrown)
  - The result is small enough to fit into a `long`. The largest value of `n` for which `n!` < Long.MAX_VALUE is 20. If the computed value exceeds `Long.MAX_VALUE` an `ArithMeticException` is thrown.

  Parameters:
    `n` - argument
  Returns:
    `n!`
  Throws:
    `java.lang.ArithmeticException` - if the result is too large to be represented by a long integer.
    `java.lang.IllegalArgumentException` - if n < 0

### factorialDouble

    public static double factorialDouble(int n)

  Returns n!. Shorthand for `n` Factorial, the product of the numbers `1,...,n` as a `double`.

  Preconditions:

  - `n >= 0` (otherwise `IllegalArgumentException` is thrown)
  - The result is small enough to fit into a `double`. The largest value of `n` for which `n!` < Double.MAX_VALUE is 170. If the computed value exceeds Double.MAX_VALUE, Double.POSITIVE_INFINITY is returned

  Parameters:
    `n` - argument
  Returns:
    `n!`
  Throws:
    `java.lang.IllegalArgumentException` - if n < 0

### factorialLog

    public static double factorialLog(int n)

  Returns the natural logarithm of n!.

  Preconditions:

  - `n >= 0` (otherwise `IllegalArgumentException` is thrown)

  Parameters:
    `n` - argument
  Returns:
    `n!`
  Throws:
    `java.lang.IllegalArgumentException` - if preconditions are not met.

### gcd

    public static int gcd(int p,
                          int q)

  Gets the greatest common divisor of the absolute value of two numbers, using the "binary gcd" method which avoids division and modulo operations. See Knuth 4.5.2 algorithm B. This algorithm is due to Josef Stein (1961).

  Special cases:
  - The invocations `gcd(Integer.MIN_VALUE, Integer.MIN_VALUE)`, `gcd(Integer.MIN_VALUE, 0)` and `gcd(0, Integer.MIN_VALUE)` throw an `ArithmeticException`, because the result would be 2^31, which is too large for an int value.
  - The result of `gcd(x, x)`, `gcd(0, x)` and `gcd(x, 0)` is the absolute value of `x`, except for the special cases above.
  - The invocation `gcd(0, 0)` is the only one which returns `0`.

  Parameters:
    `p` - any number
    `q` - any number
  Returns:
    the greatest common divisor, never negative
  Throws:
    `java.lang.ArithmeticException` - if the result cannot be represented as a nonnegative int value
  Since:
    1.1

### gcd

    public static long gcd(long p,
                           long q)

  Gets the greatest common divisor of the absolute value of two numbers, using the "binary gcd" method which avoids division and modulo operations. See Knuth 4.5.2 algorithm B. This algorithm is due to Josef Stein (1961).

  Special cases:
  - The invocations `gcd(Long.MIN_VALUE, Long.MIN_VALUE)`, `gcd(Long.MIN_VALUE, 0L)` and `gcd(0L, Long.MIN_VALUE)` throw an `ArithmeticException`, because the result would be 2^63, which is too large for a long value.
  - The result of `gcd(x, x)`, `gcd(0L, x)` and `gcd(x, 0L)` is the absolute value of `x`, except for the special cases above.
  - The invocation `gcd(0L, 0L)` is the only one which returns `0L`.

  Parameters:
    `p` - any number
    `q` - any number
  Returns:
    the greatest common divisor, never negative
  Throws:
    `java.lang.ArithmeticException` - if the result cannot be represented as a nonnegative long value
  Since:
    2.1

### hash

    public static int hash(double value)

  Returns an integer hash code representing the given double value.

  Parameters:
    `value` - the value to be hashed
  Returns:
    the hash code

### hash

    public static int hash(double[] value)

  Returns an integer hash code representing the given double array.

  Parameters:
    `value` - the value to be hashed (may be null)
  Returns:
    the hash code
  Since:
    1.2

### indicator

    public static byte indicator(byte x)

  For a byte value x, this method returns (byte)(+1) if x >= 0 and (byte)(-1) if x < 0.

  Parameters:
    `x` - the value, a byte
  Returns:
    (byte)(+1) or (byte)(-1), depending on the sign of x

### indicator

    public static double indicator(double x)

  For a double precision value x, this method returns +1.0 if x >= 0 and -1.0 if x < 0. Returns `NaN` if `x` is `NaN`.

  Parameters:
    `x` - the value, a double
  Returns:
    +1.0 or -1.0, depending on the sign of x

### indicator

    public static float indicator(float x)

  For a float value x, this method returns +1.0F if x >= 0 and -1.0F if x < 0. Returns `NaN` if `x` is `NaN`.

  Parameters:
    `x` - the value, a float
  Returns:
    +1.0F or -1.0F, depending on the sign of x

### indicator

    public static int indicator(int x)

  For an int value x, this method returns +1 if x >= 0 and -1 if x < 0.

  Parameters:
    `x` - the value, an int
  Returns:
    +1 or -1, depending on the sign of x

### indicator

    public static long indicator(long x)

  For a long value x, this method returns +1L if x >= 0 and -1L if x < 0.

  Parameters:
    `x` - the value, a long
  Returns:
    +1L or -1L, depending on the sign of x

### indicator

    public static short indicator(short x)

  For a short value x, this method returns (short)(+1) if x >= 0 and (short)(-1) if x < 0.

  Parameters:
    `x` - the value, a short
  Returns:
    (short)(+1) or (short)(-1), depending on the sign of x

### lcm

    public static int lcm(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`.

  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` - any number
    `b` - any number
  Returns:
    the least common multiple, never negative
  Throws:
    `java.lang.ArithmeticException` - if the result cannot be represented as a nonnegative int value
  Since:
    1.1

### lcm

    public static long lcm(long a,
                           long b)

  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(Long.MIN_VALUE, n)` and `lcm(n, Long.MIN_VALUE)`, where `abs(n)` is a power of 2, throw an `ArithmeticException`, because the result would be 2^63, which is too large for an int value.
  - The result of `lcm(0L, x)` and `lcm(x, 0L)` is `0L` for any `x`.

  Parameters:
    `a` - any number
    `b` - any number
  Returns:
    the least common multiple, never negative
  Throws:
    `java.lang.ArithmeticException` - if the result cannot be represented as a nonnegative long value
  Since:
    2.1

### log

    public static double log(double base,
                             double x)

  Returns the logarithm for base `b` of `x`.

  Returns `NaN`if either argument is negative. If `base` is 0 and `x` is positive, 0 is returned. If `base` is positive and `x` is 0, `Double.NEGATIVE_INFINITY` is returned. If both arguments are 0, the result is `NaN`.``

  Parameters:
    `base` - the base of the logarithm, must be greater than 0
    `x` - argument, must be greater than 0
  Returns:
    the value of the logarithm - the number y such that base^y = x.
  Since:
    1.2

### mulAndCheck

    public static int mulAndCheck(int x,
                                  int y)

  Multiply two integers, checking for overflow.

  Parameters:
    `x` - a factor
    `y` - a factor
  Returns:
    the product `x*y`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an int
  Since:
    1.1

### mulAndCheck

    public static long mulAndCheck(long a,
                                   long b)

  Multiply two long integers, checking for overflow.

  Parameters:
    `a` - first value
    `b` - second value
  Returns:
    the product `a * b`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an long
  Since:
    1.2

### nextAfter

    public static double nextAfter(double d,
                                   double direction)

  Get the next machine representable number after a number, moving in the direction of another number.

  If `direction` is greater than or equal to`d`, the smallest machine representable number strictly greater than `d` is returned; otherwise the largest representable number strictly less than `d` is returned.

  If `d` is NaN or Infinite, it is returned unchanged.

  Parameters:
    `d` - base number
    `direction` - (the only important thing is whether direction is greater or smaller than d)
  Returns:
    the next machine representable number in the specified direction
  Since:
    1.2

### scalb

    public static double scalb(double d,
                               int scaleFactor)

  Scale a number by 2scaleFactor.

  If `d` is 0 or NaN or Infinite, it is returned unchanged.

  Parameters:
    `d` - base number
    `scaleFactor` - power of two by which d sould be multiplied
  Returns:
    d × 2scaleFactor
  Since:
    2.0

### normalizeAngle

    public static double normalizeAngle(double a,
                                        double center)

  Normalize an angle in a 2&pi wide interval around a center value.

  This method has three main uses:

  - normalize an angle between 0 and 2π:
    `a = MathUtils.normalizeAngle(a, Math.PI);`
  - normalize an angle between -π and +π
    `a = MathUtils.normalizeAngle(a, 0.0);`
  - compute the angle between two defining angular positions:
    `angle = MathUtils.normalizeAngle(end, start) - start;`

  Note that due to numerical accuracy and since π cannot be represented exactly, the result interval is closed, it cannot be half-closed as would be more satisfactory in a purely mathematical view.

  Parameters:
    `a` - angle to normalize
    `center` - center of the desired 2π interval for the result
  Returns:
    a-2kπ with integer k and center-π <= a-2kπ <= center+π
  Since:
    1.2

### normalizeArray

    public static double[] normalizeArray(double[] values,
                                          double normalizedSum)
                                   throws java.lang.ArithmeticException,
                                          java.lang.IllegalArgumentException

  Normalizes an array to make it sum to a specified value. Returns the result of the transformation

          x |-> x * normalizedSum / sum

  applied to each non-NaN element x of the input array, where sum is the sum of the non-NaN entries in the input array.

  Throws IllegalArgumentException if `normalizedSum` is infinite or NaN and ArithmeticException if the input array contains any infinite elements or sums to 0

  Ignores (i.e., copies unchanged to the output array) NaNs in the input array.

  Parameters:
    `values` - input array to be normalized
    `normalizedSum` - target sum for the normalized array
  Returns:
    normalized array
  Throws:
    `java.lang.ArithmeticException` - if the input array contains infinite elements or sums to zero
    `java.lang.IllegalArgumentException` - if the target sum is infinite or NaN
  Since:
    2.1

### round

    public static double round(double x,
                               int scale)

  Round the given value to the specified number of decimal places. The value is rounded using the `BigDecimal.ROUND_HALF_UP` method.

  Parameters:
    `x` - the value to round.
    `scale` - the number of digits to the right of the decimal point.
  Returns:
    the rounded value.
  Since:
    1.1

### round

    public static double round(double x,
                               int scale,
                               int roundingMethod)

  Round the given value to the specified number of decimal places. The value is rounded using the given method which is any method defined in `BigDecimal`.

  Parameters:
    `x` - the value to round.
    `scale` - the number of digits to the right of the decimal point.
    `roundingMethod` - the rounding method as defined in `BigDecimal`.
  Returns:
    the rounded value.
  Since:
    1.1

### round

    public static float round(float x,
                              int scale)

  Round the given value to the specified number of decimal places. The value is rounding using the `BigDecimal.ROUND_HALF_UP` method.

  Parameters:
    `x` - the value to round.
    `scale` - the number of digits to the right of the decimal point.
  Returns:
    the rounded value.
  Since:
    1.1

### round

    public static float round(float x,
                              int scale,
                              int roundingMethod)

  Round the given value to the specified number of decimal places. The value is rounded using the given method which is any method defined in `BigDecimal`.

  Parameters:
    `x` - the value to round.
    `scale` - the number of digits to the right of the decimal point.
    `roundingMethod` - the rounding method as defined in `BigDecimal`.
  Returns:
    the rounded value.
  Since:
    1.1

### roundUnscaled

    private static double roundUnscaled(double unscaled,
                                        double sign,
                                        int roundingMethod)

  Round the given non-negative, value to the "nearest" integer. Nearest is determined by the rounding method specified. Rounding methods are defined in `BigDecimal`.

  Parameters:
    `unscaled` - the value to round.
    `sign` - the sign of the original, scaled value.
    `roundingMethod` - the rounding method as defined in `BigDecimal`.
  Returns:
    the rounded value.
  Since:
    1.1

### sign

    public static byte sign(byte x)

  Returns the sign for byte value `x`.

  For a byte value x, this method returns (byte)(+1) if x > 0, (byte)(0) if x = 0, and (byte)(-1) if x < 0.

  Parameters:
    `x` - the value, a byte
  Returns:
    (byte)(+1), (byte)(0), or (byte)(-1), depending on the sign of x

### sign

    public static double sign(double x)

  Returns the sign for double precision `x`.

  For a double value `x`, this method returns `+1.0` if `x > 0`, `0.0` if `x = 0.0`, and `-1.0` if `x < 0`. Returns `NaN` if `x` is `NaN`.

  Parameters:
    `x` - the value, a double
  Returns:
    +1.0, 0.0, or -1.0, depending on the sign of x

### sign

    public static float sign(float x)

  Returns the sign for float value `x`.

  For a float value x, this method returns +1.0F if x > 0, 0.0F if x = 0.0F, and -1.0F if x < 0. Returns `NaN` if `x` is `NaN`.

  Parameters:
    `x` - the value, a float
  Returns:
    +1.0F, 0.0F, or -1.0F, depending on the sign of x

### sign

    public static int sign(int x)

  Returns the sign for int value `x`.

  For an int value x, this method returns +1 if x > 0, 0 if x = 0, and -1 if x < 0.

  Parameters:
    `x` - the value, an int
  Returns:
    +1, 0, or -1, depending on the sign of x

### sign

    public static long sign(long x)

  Returns the sign for long value `x`.

  For a long value x, this method returns +1L if x > 0, 0L if x = 0, and -1L if x < 0.

  Parameters:
    `x` - the value, a long
  Returns:
    +1L, 0L, or -1L, depending on the sign of x

### sign

    public static short sign(short x)

  Returns the sign for short value `x`.

  For a short value x, this method returns (short)(+1) if x > 0, (short)(0) if x = 0, and (short)(-1) if x < 0.

  Parameters:
    `x` - the value, a short
  Returns:
    (short)(+1), (short)(0), or (short)(-1), depending on the sign of x

### sinh

    public static double sinh(double x)

  Returns the hyperbolic sine of x.

  Parameters:
    `x` - double value for which to find the hyperbolic sine
  Returns:
    hyperbolic sine of x

### subAndCheck

    public static int subAndCheck(int x,
                                  int y)

  Subtract two integers, checking for overflow.

  Parameters:
    `x` - the minuend
    `y` - the subtrahend
  Returns:
    the difference `x-y`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an int
  Since:
    1.1

### subAndCheck

    public static long subAndCheck(long a,
                                   long b)

  Subtract two long integers, checking for overflow.

  Parameters:
    `a` - first value
    `b` - second value
  Returns:
    the difference `a-b`
  Throws:
    `java.lang.ArithmeticException` - if the result can not be represented as an long
  Since:
    1.2

### pow

    public static int pow(int k,
                          int e)
                   throws java.lang.IllegalArgumentException

  Raise an int to an int power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static int pow(int k,
                          long e)
                   throws java.lang.IllegalArgumentException

  Raise an int to a long power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static long pow(long k,
                           int e)
                    throws java.lang.IllegalArgumentException

  Raise a long to an int power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static long pow(long k,
                           long e)
                    throws java.lang.IllegalArgumentException

  Raise a long to a long power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static java.math.BigInteger pow(java.math.BigInteger k,
                                           int e)
                                    throws java.lang.IllegalArgumentException

  Raise a BigInteger to an int power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static java.math.BigInteger pow(java.math.BigInteger k,
                                           long e)
                                    throws java.lang.IllegalArgumentException

  Raise a BigInteger to a long power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### pow

    public static java.math.BigInteger pow(java.math.BigInteger k,
                                           java.math.BigInteger e)
                                    throws java.lang.IllegalArgumentException

  Raise a BigInteger to a BigInteger power.

  Parameters:
    `k` - number to raise
    `e` - exponent (must be positive or null)
  Returns:
    ke
  Throws:
    `java.lang.IllegalArgumentException` - if e is negative

### distance1

    public static double distance1(double[] p1,
                                   double[] p2)

  Calculates the L1 (sum of abs) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L1 distance between the two points

### distance1

    public static int distance1(int[] p1,
                                int[] p2)

  Calculates the L1 (sum of abs) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L1 distance between the two points

### distance

    public static double distance(double[] p1,
                                  double[] p2)

  Calculates the L2 (Euclidean) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L2 distance between the two points

### distance

    public static double distance(int[] p1,
                                  int[] p2)

  Calculates the L2 (Euclidean) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L2 distance between the two points

### distanceInf

    public static double distanceInf(double[] p1,
                                     double[] p2)

  Calculates the L∞ (max of abs) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L∞ distance between the two points

### distanceInf

    public static int distanceInf(int[] p1,
                                  int[] p2)

  Calculates the L∞ (max of abs) distance between two points.

  Parameters:
    `p1` - the first point
    `p2` - the second point
  Returns:
    the L∞ distance between the two points

### checkOrder

    public static void checkOrder(double[] val,
                                  int dir,
                                  boolean strict)

  Checks that the given array is sorted.

  Parameters:
    `val` - Values
    `dir` - Order direction (-1 for decreasing, 1 for increasing)
    `strict` - Whether the order should be strict
  Throws:
    `java.lang.IllegalArgumentException` - if the array is not sorted.

Copyright (c) 2003-2011 Apache Software Foundation