org.hipparchus.util

## Class MathUtils

• ### Nested Class Summary

Nested Classes
Modifier and Type Class and Description
static class  MathUtils.FieldSumAndResidual<T extends FieldElement<T>>
Result class for twoSum(FieldElement, FieldElement) containing the sum and the residual error in the sum.
static class  MathUtils.SumAndResidual
Result class for twoSum(double, double) containing the sum and the residual error in the sum.
• ### Field Summary

Fields
Modifier and Type Field and Description
static double PI_SQUARED
$$\pi^2$$
static double SEMI_PI
$$\pi/2$$.
static double TWO_PI
$$2\pi$$
• ### Method Summary

All Methods
Modifier and Type Method and Description
static void checkDimension(int dimension, int otherDimension)
Checks that the given dimensions match.
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 void checkRangeInclusive(double value, double lo, double hi)
Checks that the given value is strictly within the range [lo, hi].
static void checkRangeInclusive(long value, long lo, long hi)
Checks that the given value is strictly within the range [lo, hi].
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 boolean equals(double x, double y)
Returns true if the values are equal according to semantics of Double.equals(Object).
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 <T extends CalculusFieldElement<T>>T max(T e1, T e2)
Find the maximum of two field elements.
static <T extends CalculusFieldElement<T>>T min(T e1, T e2)
Find the minimum of two field elements.
static double normalizeAngle(double a, double center)
Normalize an angle in a 2π wide interval around a center value.
static <T extends CalculusFieldElement<T>>T normalizeAngle(T a, T center)
Normalize an angle in a 2π wide interval around a center value.
static double reduce(double a, double period, double offset)
Reduce |a - offset| to the primary interval [0, |period|).
static MathUtils.SumAndResidual twoSum(double a, double b)
Sums a and b using Møller's 2Sum algorithm.
static <T extends FieldElement<T>>MathUtils.FieldSumAndResidual<T> twoSum(T a, T b)
Sums a and b using Møller's 2Sum algorithm.
• ### 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
$$2\pi$$
Constant Field Values
• #### PI_SQUARED

public static final double PI_SQUARED
$$\pi^2$$
Constant Field Values
• #### SEMI_PI

public static final double SEMI_PI
$$\pi/2$$.
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
• #### equals

public static boolean equals(double x,
double y)
Returns true if the values are equal according to semantics of Double.equals(Object).
Parameters:
x - Value
y - Value
Returns:
new Double(x).equals(new Double(y))
• #### 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
• #### normalizeAngle

public static double normalizeAngle(double a,
double center)
Normalize an angle in a 2π wide interval around a center value.

This method has three main uses:

• normalize an angle between 0 and 2π:
a = MathUtils.normalizeAngle(a, FastMath.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
• #### normalizeAngle

public static <T extends CalculusFieldElement<T>> T normalizeAngle(T a,
T center)
Normalize an angle in a 2π wide interval around a center value.

This method has three main uses:

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

Type Parameters:
T - the type of the field elements
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
• #### max

public static <T extends CalculusFieldElement<T>> T max(T e1,
T e2)
Find the maximum of two field elements.
Type Parameters:
T - the type of the field elements
Parameters:
e1 - first element
e2 - second element
Returns:
max(a1, e2)
• #### min

public static <T extends CalculusFieldElement<T>> T min(T e1,
T e2)
Find the minimum of two field elements.
Type Parameters:
T - the type of the field elements
Parameters:
e1 - first element
e2 - second element
Returns:
min(a1, e2)
• #### 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 MathRuntimeException
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:
MathRuntimeException - if magnitude == Byte.MIN_VALUE and sign >= 0.
• #### copySign

public static short copySign(short magnitude,
short sign)
throws MathRuntimeException
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:
MathRuntimeException - if magnitude == Short.MIN_VALUE and sign >= 0.
• #### copySign

public static int copySign(int magnitude,
int sign)
throws MathRuntimeException
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:
MathRuntimeException - if magnitude == Integer.MIN_VALUE and sign >= 0.
• #### copySign

public static long copySign(long magnitude,
long sign)
throws MathRuntimeException
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:
MathRuntimeException - if magnitude == Long.MIN_VALUE and sign >= 0.
• #### checkFinite

public static void checkFinite(double x)
throws MathIllegalArgumentException
Check that the argument is a real number.
Parameters:
x - Argument.
Throws:
MathIllegalArgumentException - if x is not a finite real number.
• #### checkFinite

public static void checkFinite(double[] val)
throws MathIllegalArgumentException
Check that all the elements are real numbers.
Parameters:
val - Arguments.
Throws:
MathIllegalArgumentException - 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.
• #### checkRangeInclusive

public static void checkRangeInclusive(long value,
long lo,
long hi)
Checks that the given value is strictly within the range [lo, hi].
Parameters:
value - value to be checked.
lo - the lower bound (inclusive).
hi - the upper bound (inclusive).
Throws:
MathIllegalArgumentException - if value is strictly outside [lo, hi].
• #### checkRangeInclusive

public static void checkRangeInclusive(double value,
double lo,
double hi)
Checks that the given value is strictly within the range [lo, hi].
Parameters:
value - value to be checked.
lo - the lower bound (inclusive).
hi - the upper bound (inclusive).
Throws:
MathIllegalArgumentException - if value is strictly outside [lo, hi].
• #### checkDimension

public static void checkDimension(int dimension,
int otherDimension)
Checks that the given dimensions match.
Parameters:
dimension - the first dimension.
otherDimension - the second dimension.
Throws:
MathIllegalArgumentException - if length != otherLength.
• #### twoSum

public static MathUtils.SumAndResidual twoSum(double a,
double b)
Sums a and b using Møller's 2Sum algorithm.

References:

• Møller, Ole. "Quasi double-precision in floating point addition." BIT 5, 37–50 (1965).
• Shewchuk, Richard J. "Adaptive Precision Floating-Point Arithmetic and Fast Robust Geometric Predicates." Discrete & Computational Geometry 18, 305–363 (1997).
• https://en.wikipedia.org/wiki/2Sum
Parameters:
a - first summand
b - second summand
Returns:
sum and residual error in the sum
• #### twoSum

public static <T extends FieldElement<T>> MathUtils.FieldSumAndResidual<T> twoSum(T a,
T b)
Sums a and b using Møller's 2Sum algorithm.

References:

• Møller, Ole. "Quasi double-precision in floating point addition." BIT 5, 37–50 (1965).
• Shewchuk, Richard J. "Adaptive Precision Floating-Point Arithmetic and Fast Robust Geometric Predicates." Discrete & Computational Geometry 18, 305–363 (1997).
• https://en.wikipedia.org/wiki/2Sum
Type Parameters:
T - field element type
Parameters:
a - first summand
b - second summand
Returns:
sum and residual error in the sum
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