Package org.hipparchus.geometry.spherical.twod

Class S2Point

java.lang.Object

org.hipparchus.geometry.spherical.twod.S2Point

All Implemented Interfaces:

Serializable, Point<Sphere2D>

public class S2Point
extends Object
implements Point<Sphere2D>

This class represents a point on the 2-sphere.

We use the mathematical convention to use the azimuthal angle \( \theta \) in the x-y plane as the first coordinate, and the polar angle \( \varphi \) as the second coordinate (see Spherical Coordinates in MathWorld).

Instances of this class are guaranteed to be immutable.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final S2Point	MINUS_I	-I (coordinates: \( \theta = \pi, \varphi = \pi/2 \)).
static final S2Point	MINUS_J	-J (coordinates: \( \theta = 3\pi/2, \varphi = \pi/2 \)).
static final S2Point	MINUS_K	-K (coordinates: \( \theta = any angle, \varphi = \pi \)).
static final S2Point	NaN	A vector with all coordinates set to NaN.
static final S2Point	PLUS_I	+I (coordinates: \( \theta = 0, \varphi = \pi/2 \)).
static final S2Point	PLUS_J	+J (coordinates: \( \theta = \pi/2, \varphi = \pi/2 \))).
static final S2Point	PLUS_K	+K (coordinates: \( \theta = any angle, \varphi = 0 \)).

Constructor Summary

Constructors

Constructor	Description
S2Point(double theta, double phi)	Simple constructor.
S2Point(Vector3D vector)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
double	distance(Point<Sphere2D> point)	Compute the distance between the instance and another point.
static double	distance(S2Point p1, S2Point p2)	Compute the distance (angular separation) between two points.
boolean	equals(Object other)	Test for the equality of two points on the 2-sphere.
boolean	equalsIeee754(Object other)	Test for the equality of two points on the 2-sphere.
double	getPhi()	Get the polar angle \( \varphi \).
Space	getSpace()	Get the space to which the point belongs.
double	getTheta()	Get the azimuthal angle \( \theta \) in the x-y plane.
Vector3D	getVector()	Get the corresponding normalized vector in the 3D euclidean space.
int	hashCode()	Get a hashCode for the point.
boolean	isNaN()	Returns true if any coordinate of this point is NaN; false otherwise
S2Point	negate()	Get the opposite of the instance.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

PLUS_I

public static final S2Point PLUS_I

+I (coordinates: \( \theta = 0, \varphi = \pi/2 \)).

PLUS_J

public static final S2Point PLUS_J

+J (coordinates: \( \theta = \pi/2, \varphi = \pi/2 \))).

PLUS_K

public static final S2Point PLUS_K

+K (coordinates: \( \theta = any angle, \varphi = 0 \)).

MINUS_I

public static final S2Point MINUS_I

-I (coordinates: \( \theta = \pi, \varphi = \pi/2 \)).

MINUS_J

public static final S2Point MINUS_J

-J (coordinates: \( \theta = 3\pi/2, \varphi = \pi/2 \)).

MINUS_K

public static final S2Point MINUS_K

-K (coordinates: \( \theta = any angle, \varphi = \pi \)).

NaN

public static final S2Point NaN

A vector with all coordinates set to NaN.

Constructor Details

S2Point

public S2Point(double theta,
 double phi)
        throws MathIllegalArgumentException

Simple constructor. Build a vector from its spherical coordinates

Parameters:

theta - azimuthal angle \( \theta \) in the x-y plane

phi - polar angle \( \varphi \)

Throws:

MathIllegalArgumentException - if \( \varphi \) is not in the [\( 0; \pi \)] range

See Also:

• getTheta()
• getPhi()

S2Point

public S2Point(Vector3D vector)
        throws MathRuntimeException

Simple constructor. Build a vector from its underlying 3D vector

Parameters:

vector - 3D vector

Throws:

MathRuntimeException - if vector norm is zero

Method Details

getTheta

public double getTheta()

Get the azimuthal angle \( \theta \) in the x-y plane.

Returns:

azimuthal angle \( \theta \) in the x-y plane

See Also:

• S2Point(double, double)

getPhi

public double getPhi()

Get the polar angle \( \varphi \).

Returns:

polar angle \( \varphi \)

See Also:

• S2Point(double, double)

getVector

public Vector3D getVector()

Get the corresponding normalized vector in the 3D euclidean space.

Returns:

normalized vector

getSpace

public Space getSpace()

Get the space to which the point belongs.

Specified by:

getSpace in interface Point<Sphere2D>

Returns:

containing space

isNaN

public boolean isNaN()

Returns true if any coordinate of this point is NaN; false otherwise

Specified by:

isNaN in interface Point<Sphere2D>

Returns:

true if any coordinate of this point is NaN; false otherwise

negate

public S2Point negate()

Get the opposite of the instance.

Returns:

a new vector which is opposite to the instance

distance

public double distance(Point<Sphere2D> point)

Compute the distance between the instance and another point.

Specified by:

distance in interface Point<Sphere2D>

Parameters:

point - second point

Returns:

the distance between the instance and p

distance

public static double distance(S2Point p1,
 S2Point p2)

Compute the distance (angular separation) between two points.

Parameters:

p1 - first vector

p2 - second vector

Returns:

the angular separation between p1 and p2

equals

public boolean equals(Object other)

Test for the equality of two points on the 2-sphere.

If all coordinates of two points are exactly the same, and none are Double.NaN, the two points are considered to be equal.

NaN coordinates are considered to affect globally the point and be equals to each other - i.e, if either (or all) coordinates of the point are equal to Double.NaN, the point is equal to NaN.

Overrides:

equals in class Object

Parameters:

other - Object to test for equality to this

Returns:

true if two points on the 2-sphere objects are equal, false if object is null, not an instance of S2Point, or not equal to this S2Point instance

equalsIeee754

public boolean equalsIeee754(Object other)

Test for the equality of two points on the 2-sphere.

If all coordinates of two points are exactly the same, and none are Double.NaN, the two points are considered to be equal.

In compliance with IEEE754 handling, if any coordinates of any of the two points are NaN, then the points are considered different. This implies that S2Point.NaN.equals(S2Point.NaN) returns false despite the instance is checked against itself.

Parameters:

other - Object to test for equality to this

Returns:

true if two points objects are equal, false if object is null, not an instance of S2Point, or not equal to this S2Point instance

Since:

2.1

hashCode

public int hashCode()

Get a hashCode for the point.

All NaN values have the same hash code.

Overrides:

hashCode in class Object

Returns:

a hash code value for this object

toString

public String toString()

Overrides:

toString in class Object