uk.ac.starlink.ttools.plot2.geom

Class Rotation

java.lang.Object

uk.ac.starlink.ttools.plot2.geom.Rotation

@Equality
public abstract class Rotation
extends Object

Rotates vectors between sky systems.

Since:

20 Apr 2016

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static Rotation	IDENTITY Identity rotation; the rotate method is a no-op.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Rotation() Protected no-arg constructor of abstract class.

Method Summary

Modifier and Type	Method and Description
static Rotation	createRotation(SkySys inSys, SkySys outSys) Returns a rotation instance that can transform between two submitted sky systems.
abstract double[]	getMatrix() Returns the 9-element matrix defining this rotation.
abstract Rotation	invert() Returns the inverse of this rotation.
static boolean	isIdentityRotation(SkySys inSys, SkySys outSys) Indicates whether the rotation between two sky systems is known to be an identity (no-op) transformation.
abstract void	rotate(double[] r3) Rotates a 3-vector in place.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

IDENTITY

public static Rotation IDENTITY

Identity rotation; the rotate method is a no-op.

Constructor Detail

Rotation

protected Rotation()

Protected no-arg constructor of abstract class.

Method Detail

rotate

public abstract void rotate(double[] r3)

Rotates a 3-vector in place.

Parameters:

r3 - 3-element unit vector, changed on output

invert

public abstract Rotation invert()

Returns the inverse of this rotation.

Returns:

inverse rotation

getMatrix

public abstract double[] getMatrix()

Returns the 9-element matrix defining this rotation.

Returns:

9-element rotation matrix

isIdentityRotation

public static boolean isIdentityRotation(SkySys inSys,
                                         SkySys outSys)

Indicates whether the rotation between two sky systems is known to be an identity (no-op) transformation. If either or both sky systems is null, it is assumed that no rotation is required.

Parameters:

inSys - input sky system; may be null

outSys - output sky system; may be null

Returns:

true iff no rotation operation is required

createRotation

public static Rotation createRotation(SkySys inSys,
                                      SkySys outSys)

Returns a rotation instance that can transform between two submitted sky systems.

Parameters:

inSys - input sky system; may be null

outSys - output sky system; may be null

Returns:

rotation from input to output sky systems, not null