Package talonsoalbi_at_gmail_dot_com.ssoxmatch.ephem

Class LocationElement

java.lang.Object

talonsoalbi_at_gmail_dot_com.ssoxmatch.ephem.LocationElement

All Implemented Interfaces:

java.io.Serializable

public class LocationElement
extends java.lang.Object
implements java.io.Serializable

This is a convenience class used for passing around spherical coordinates. Units are radians for longitude and latitude, AU for distance.

Author:

talonso

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
LocationElement()	Default constructor.
LocationElement(double[] vector)	Vector constructor.
LocationElement(double lon, double lat, double rad)	Explicit constructor.

Method Summary

Modifier and Type	Method	Description
LocationElement	clone()	To clone the object.
boolean	equals(java.lang.Object o)	Returns true if the input object is equals to this instance.
double[]	get()	Get all values in this instance as a vector.
static double	getAngularDistance(LocationElement loc1, LocationElement loc2)	Obtain angular distance between two spherical coordinates.
static double	getApproximateAngularDistance(LocationElement loc1, LocationElement loc2)	Obtain approximate angular distance between two spherical coordinates.
static double	getApproximatePositionAngle(LocationElement loc1, LocationElement loc2)	Obtain position angle between two spherical coordinates.
double	getLatitude()	Gets the latitude.
static double	getLinearDistance(LocationElement loc1, LocationElement loc2)	Obtain linear distance between two spherical positions.
double	getLongitude()	Gets the longitude.
static LocationElement	getMidPoint(LocationElement loc1, LocationElement loc2)	Obtain the direction between two spherical positions.
static double	getPositionAngle(LocationElement loc1, LocationElement loc2)	Obtain exact position angle between two spherical coordinates.
double	getRadius()	Gets the radius.
double[]	getRectangularCoordinates()	Transforms a LocationElement into a set of rectangular coordinates x, y, z.
int	hashCode()
void	move(double dlon, double dlat, double dr)	Moves this position a given amount in each axis.
static double[]	parseLocationElement(LocationElement loc)	Transforms a LocationElement into a set of rectangular coordinates x, y, z.
static double[]	parseLocationElementFast(LocationElement loc)	Transforms a LocationElement into a set of rectangular coordinates x, y, z, using approximate trigonometric functions.
static LocationElement	parseRectangularCoordinates(double[] v)	Transforms rectangular coordinates x, y, z contained in an array to a LocationElement.
static LocationElement	parseRectangularCoordinates(double x, double y, double z)	Transforms rectangular coordinates x, y, z to a LocationElement.
static LocationElement	parseRectangularCoordinatesFast(double[] v)	Transforms rectangular coordinates x, y, z contained in an array to a LocationElement.
static LocationElement	parseRectangularCoordinatesFast(double x, double y, double z)	Transforms rectangular coordinates x, y, z contained in an array to a LocationElement.
void	set(double[] vector)	Set all members of this instance from a vector.
void	set(double lon, double lat, double rad)	Set all members of this instance individually.
void	setRadius(double d)	Set the radius.
static double	solveSphericalTriangle(LocationElement locA, LocationElement locP, LocationElement locP1, boolean approx)	Solves an spherical triangle return the angle between the positions locP and locP1 as seen from locA.
void	toOffset(double dlon, double dlat)	Moves this position a given amount in each axis, setting the location to a given point with some offset.
java.lang.String	toString()	Returns a String representation of this object.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

LocationElement

public LocationElement()

Default constructor.

LocationElement

public LocationElement(double lon,
                       double lat,
                       double rad)

Explicit constructor.

Parameters:

lon - longitude.

lat - latitude.

rad - radius.

LocationElement

public LocationElement(double[] vector)

Vector constructor.

Parameters:

vector - { lon, lat, rad }

Method Detail

getLatitude

public double getLatitude()

Gets the latitude.

Returns:

The latitude value of this instance.

getLongitude

public double getLongitude()

Gets the longitude.

Returns:

The longitude value of this instance.

getRadius

public double getRadius()

Gets the radius.

Returns:

The radius value of this instance.

get

public double[] get()

Get all values in this instance as a vector.

The vector is an array of three doubles, longitude, latitude, radius.

Returns:

v[0] = longitude, v[1] = latitude, v[2] = radius.

setRadius

public void setRadius(double d)

Set the radius.

Parameters:

d - The new radius value.

set

public void set(double[] vector)

Set all members of this instance from a vector.

The vector is an array of three doubles, longitude, latitude, radius, in that order.

Parameters:

vector - v[0] = longitude, v[1] = latitude, v[2] = radius.

set

public void set(double lon,
                double lat,
                double rad)

Set all members of this instance individually.

Parameters:

lon - The new longitude.

lat - The new latitude.

rad - The new radius.

parseRectangularCoordinates

public static LocationElement parseRectangularCoordinates(double[] v)

Transforms rectangular coordinates x, y, z contained in an array to a LocationElement. Coordinate system is independent: equatorial, ecliptic, or any other.

Parameters:

v - (x, y, z) vector.

Returns:

Location object.

parseRectangularCoordinatesFast

public static LocationElement parseRectangularCoordinatesFast(double[] v)

Transforms rectangular coordinates x, y, z contained in an array to a LocationElement. Coordinate system is independent: equatorial, ecliptic, or any other. This method uses FastMath.atan2(double, double) and FastMath.asin(double) methods.

Parameters:

v - (x, y, z) vector.

Returns:

Location object.

parseRectangularCoordinatesFast

public static LocationElement parseRectangularCoordinatesFast(double x,
                                                              double y,
                                                              double z)

Transforms rectangular coordinates x, y, z contained in an array to a LocationElement. Coordinate system is independent: equatorial, ecliptic, or any other. This method calls parseRectangularCoordinatesFast(double[]).

Parameters:

x - X coordinate.

y - Y coordinate.

z - Z coordinate.

Returns:

Location object.

parseRectangularCoordinates

public static LocationElement parseRectangularCoordinates(double x,
                                                          double y,
                                                          double z)

Transforms rectangular coordinates x, y, z to a LocationElement. Coordinate system is independent: equatorial, ecliptic, or any other.

Parameters:

x - X coordinate.

y - Y coordinate.

z - Z coordinate.

Returns:

Location object.

parseLocationElement

public static double[] parseLocationElement(LocationElement loc)

Transforms a LocationElement into a set of rectangular coordinates x, y, z.

Parameters:

loc - Location object.

Returns:

Array with (x, y, z) vector.

parseLocationElementFast

public static double[] parseLocationElementFast(LocationElement loc)

Transforms a LocationElement into a set of rectangular coordinates x, y, z, using approximate trigonometric functions.

Parameters:

loc - Location object.

Returns:

Array with (x, y, z) vector.

getRectangularCoordinates

public double[] getRectangularCoordinates()

Transforms a LocationElement into a set of rectangular coordinates x, y, z.

Returns:

Array with (x, y, z) vector.

getLinearDistance

public static double getLinearDistance(LocationElement loc1,
                                       LocationElement loc2)

Obtain linear distance between two spherical positions.

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

Linear distance.

getMidPoint

public static LocationElement getMidPoint(LocationElement loc1,
                                          LocationElement loc2)

Obtain the direction between two spherical positions.

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

The midpoint.

solveSphericalTriangle

public static double solveSphericalTriangle(LocationElement locA,
                                            LocationElement locP,
                                            LocationElement locP1,
                                            boolean approx)

Solves an spherical triangle return the angle between the positions locP and locP1 as seen from locA.

Parameters:

locA - A position.

locP - P position.

locP1 - P1 position.

approx - True for an approximate and faster computation.

Returns:

The spherical angle.

getAngularDistance

public static double getAngularDistance(LocationElement loc1,
                                        LocationElement loc2)

Obtain angular distance between two spherical coordinates.

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

The distance in radians, from 0 to PI.

getApproximateAngularDistance

public static double getApproximateAngularDistance(LocationElement loc1,
                                                   LocationElement loc2)

Obtain approximate angular distance between two spherical coordinates. Almost exact result

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

The distance in radians, from 0 to PI.

getApproximatePositionAngle

public static double getApproximatePositionAngle(LocationElement loc1,
                                                 LocationElement loc2)

Obtain position angle between two spherical coordinates. Good performance.

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

The position angle in radians.

getPositionAngle

public static double getPositionAngle(LocationElement loc1,
                                      LocationElement loc2)

Obtain exact position angle between two spherical coordinates. Performance will be poor.

Parameters:

loc1 - Location object.

loc2 - Location object.

Returns:

The position angle in radians.

clone

public LocationElement clone()

To clone the object.

equals

public boolean equals(java.lang.Object o)

Returns true if the input object is equals to this instance.

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Returns a String representation of this object.

Overrides:

toString in class java.lang.Object

move

public void move(double dlon,
                 double dlat,
                 double dr)

Moves this position a given amount in each axis.

Parameters:

dlon - Displacement in longitude, radians. It is a pure incremental modification.

dlat - Displacement in latitude, radians.

dr - Displacemente in distance, in units of the distance.

toOffset

public void toOffset(double dlon,
                     double dlat)

Moves this position a given amount in each axis, setting the location to a given point with some offset.

Parameters:

dlon - Displacement in longitude, radians. This increment is respect the sky plain, not a coordinate incremental offset.

dlat - Displacement in latitude, radians.