astro
Class SimpleSol

java.lang.Object
  astro.SimpleSol

All Implemented Interfaces:

SolarPosition

public class SimpleSol
extends Object
implements SolarPosition

A class implementing SolarPosition. It uses a very simple algorithm to calculate the Sun's celestial position.

See Also:

sunpos

Nested Class Summary

static class

SimpleSol.Test Test purpose.

Nested classes/interfaces inherited from interface astro.SolarPosition

SolarPosition.Plato

Field Summary

private static double	ASUN The constant coefficient.
private static double	BSUN The linear coefficient.
private Date	Clock The date used for the calculations.
private static double	CSUN The quadratic coefficient.
private double	Dec Declination of Sun, radians.
private static double	LAM Constant for excentricity offset.
private double	Lambda Ecliptical longitude of the Sun, radians.
private static double	NYA Constant coefficient for calculating mean anamoly.
private static double	NYB Linear coefficient for calculating mean anamoly.
private static double	NYC Quadratic coefficient for calculating mean anamoly.
private double	Ra Right ascension of the Sun, radians.
private boolean	RaDecValid A boolean marking the availability of ra and declination.

Constructor Summary

SimpleSol()
Constructs an invalid solar position instance.

SimpleSol(Date time)
Constructs a solar position instance with a specified date.

Method Summary

protected void	calcLambda() Calculates the ecliptical longitude of the Sun and transfers it into Lambda.
protected void	calcRaDec() Calculates the right ascension and the declination of an object with the given ecliptical longitude and a latitude of zero.
double	getDec() Returns the declination of the Sun.
double	getEclipticalLongitude() Returns the ecliptical longitude of the Sun.
double	getRa() Returns the right ascension of the Sun.
void	setDate(Date time) Sets the date for which the Sun's position should be evaluated.

Methods inherited from class java.lang.Object

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

Field Detail

ASUN

private static final double ASUN

The constant coefficient.

See Also:

Constant Field Values

BSUN

private static final double BSUN

The linear coefficient.

See Also:

Constant Field Values

CSUN

private static final double CSUN

The quadratic coefficient.

See Also:

Constant Field Values

LAM

private static final double LAM

Constant for excentricity offset.

See Also:

Constant Field Values

NYA

private static final double NYA

Constant coefficient for calculating mean anamoly.

See Also:

Constant Field Values

NYB

private static final double NYB

Linear coefficient for calculating mean anamoly.

See Also:

Constant Field Values

NYC

private static final double NYC

Quadratic coefficient for calculating mean anamoly.

See Also:

Constant Field Values

Lambda

private double Lambda

Ecliptical longitude of the Sun, radians.

RaDecValid

private boolean RaDecValid

A boolean marking the availability of ra and declination.

Ra

private double Ra

Right ascension of the Sun, radians.

Dec

private double Dec

Declination of Sun, radians.

Clock

private Date Clock

The date used for the calculations.

Constructor Detail

SimpleSol

public SimpleSol()

Constructs an invalid solar position instance. Use of this constructor requires the time to be set with setDate(java.util.Date) before calling any of the position retrieving methods, or an IllegalStateException will be thrown.

SimpleSol

public SimpleSol(Date time)

Constructs a solar position instance with a specified date. With this constructor, all positional retrieving methods can be used instantely.

Method Detail

setDate

public void setDate(Date time)

Sets the date for which the Sun's position should be evaluated. Additionally calculates the ecliptical longitude of the Sun. Invalids ra and dec of the Sun, regardless of equality of this date to the former call to this method.

Specified by:

setDate in interface SolarPosition

Parameters:

time - The date used for calculating the Sun's position.

calcLambda

protected void calcLambda()

Calculates the ecliptical longitude of the Sun and transfers it into Lambda. This method is protected to allow subclasses to interfere with the lambda calculation. It is onlt called after a set of the time with setDate(java.util.Date), therefore a valid date always means a valid lambda.

This method is quadratic in time.

getEclipticalLongitude

public double getEclipticalLongitude()

Returns the ecliptical longitude of the Sun. If this method is called without a prior call to setDate, this method throws an IllegalStateException.

Specified by:

getEclipticalLongitude in interface SolarPosition

Returns:

The ecliptical longitude in radians, confined to 0 to 2PI.

getRa

public double getRa()

Returns the right ascension of the Sun. This method uses a flag to remember prior calls to getRa or getDec to speed up multiple use of this methods.

If this method is called without a prior call to setDate, this method throws an IllegalStateException.

Specified by:

getRa in interface SolarPosition

Returns:

The right ascension in radians, confined to 0 to 2PI.

getDec

public double getDec()

Returns the declination of the Sun. This method uses a flag to remember prior calls to getRa or getDec to speed up multiple use of this methods.

If this method is called without a prior call to setDate, this method throws an IllegalStateException.

Specified by:

getDec in interface SolarPosition

Returns:

The declination in radians.

calcRaDec

protected void calcRaDec()

Calculates the right ascension and the declination of an object with the given ecliptical longitude and a latitude of zero. Relies on a valid Lambda.