org.apache.commons.math3.util
Class MathUtils

java.lang.Object
  extended by org.apache.commons.math3.util.MathUtils

public final class MathUtils
extends Object

Miscellaneous utility functions.

Version:
$Id: MathUtils.java 1416643 2012-12-03 19:37:14Z tn $
See Also:
ArithmeticUtils, Precision, MathArrays

Field Summary
static double TWO_PI
          2 π.
 
Method Summary
static void checkFinite(double x)
          Check that the argument is a real number.
static void checkFinite(double[] val)
          Check that all the elements are real numbers.
static void checkNotNull(Object o)
          Checks that an object is not null.
static void checkNotNull(Object o, Localizable pattern, Object... args)
          Checks that an object is not null.
static byte copySign(byte magnitude, byte sign)
          Returns the first argument with the sign of the second argument.
static int copySign(int magnitude, int sign)
          Returns the first argument with the sign of the second argument.
static long copySign(long magnitude, long sign)
          Returns the first argument with the sign of the second argument.
static short copySign(short magnitude, short sign)
          Returns the first argument with the sign of the second argument.
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 double normalizeAngle(double a, double center)
          Normalize an angle in a 2&pi wide interval around a center value.
static double reduce(double a, double period, double offset)
          Reduce |a - offset| to the primary interval [0, |period|).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

TWO_PI

public static final double TWO_PI
2 π.

Since:
2.1
See Also:
Constant Field Values
Method Detail

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

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:

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

reduce

public static double reduce(double a,
                            double period,
                            double offset)

Reduce |a - offset| to the primary interval [0, |period|).

Specifically, the value returned is
a - |period| * floor((a - offset) / |period|) - offset.

If any of the parameters are NaN or infinite, the result is NaN.

Parameters:
a - Value to reduce.
period - Period.
offset - Value that will be mapped to 0.
Returns:
the value, within the interval [0 |period|), that corresponds to a.

copySign

public static byte copySign(byte magnitude,
                            byte sign)
                     throws MathArithmeticException
Returns the first argument with the sign of the second argument.

Parameters:
magnitude - Magnitude of the returned value.
sign - Sign of the returned value.
Returns:
a value with magnitude equal to magnitude and with the same sign as the sign argument.
Throws:
MathArithmeticException - if magnitude == Byte.MIN_VALUE and sign >= 0.

copySign

public static short copySign(short magnitude,
                             short sign)
                      throws MathArithmeticException
Returns the first argument with the sign of the second argument.

Parameters:
magnitude - Magnitude of the returned value.
sign - Sign of the returned value.
Returns:
a value with magnitude equal to magnitude and with the same sign as the sign argument.
Throws:
MathArithmeticException - if magnitude == Short.MIN_VALUE and sign >= 0.

copySign

public static int copySign(int magnitude,
                           int sign)
                    throws MathArithmeticException
Returns the first argument with the sign of the second argument.

Parameters:
magnitude - Magnitude of the returned value.
sign - Sign of the returned value.
Returns:
a value with magnitude equal to magnitude and with the same sign as the sign argument.
Throws:
MathArithmeticException - if magnitude == Integer.MIN_VALUE and sign >= 0.

copySign

public static long copySign(long magnitude,
                            long sign)
                     throws MathArithmeticException
Returns the first argument with the sign of the second argument.

Parameters:
magnitude - Magnitude of the returned value.
sign - Sign of the returned value.
Returns:
a value with magnitude equal to magnitude and with the same sign as the sign argument.
Throws:
MathArithmeticException - if magnitude == Long.MIN_VALUE and sign >= 0.

checkFinite

public static void checkFinite(double x)
                        throws NotFiniteNumberException
Check that the argument is a real number.

Parameters:
x - Argument.
Throws:
NotFiniteNumberException - if x is not a finite real number.

checkFinite

public static void checkFinite(double[] val)
                        throws NotFiniteNumberException
Check that all the elements are real numbers.

Parameters:
val - Arguments.
Throws:
NotFiniteNumberException - if any values of the array is not a finite real number.

checkNotNull

public static void checkNotNull(Object o,
                                Localizable pattern,
                                Object... args)
                         throws NullArgumentException
Checks that an object is not null.

Parameters:
o - Object to be checked.
pattern - Message pattern.
args - Arguments to replace the placeholders in pattern.
Throws:
NullArgumentException - if o is null.

checkNotNull

public static void checkNotNull(Object o)
                         throws NullArgumentException
Checks that an object is not null.

Parameters:
o - Object to be checked.
Throws:
NullArgumentException - if o is null.


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