uk.ac.starlink.ttools.func

Class CoordsDegrees

java.lang.Object

uk.ac.starlink.ttools.func.CoordsDegrees

public class CoordsDegrees
extends Object

Functions for angle transformations and manipulations, with angles generally in degrees. In particular, methods for translating between degrees and HH:MM:SS.S or DDD:MM:SS.S type sexagesimal representations are provided.

Since:

11 Oct 2011

Author:

Mark Taylor

Method Summary

Modifier and Type	Method and Description
static String	degreesToDms(double deg) Converts an angle in degrees to a formatted degrees:minutes:seconds string.
static String	degreesToDms(double deg, int secFig) Converts an angle in degrees to a formatted degrees:minutes:seconds string with a given number of decimal places in the seconds field.
static String	degreesToHms(double deg) Converts an angle in degrees to a formatted hours:minutes:seconds string.
static String	degreesToHms(double deg, int secFig) Converts an angle in degrees to a formatted hours:minutes:seconds string with a given number of decimal places in the seconds field.
static double	dmsToDegrees(double deg, double min, double sec) Converts degrees, minutes, seconds to an angle in degrees.
static double	dmsToDegrees(String dms) Converts a formatted degrees:minutes:seconds string to an angle in degrees.
static double	hmsToDegrees(double hour, double min, double sec) Converts hours, minutes, seconds to an angle in degrees.
static double	hmsToDegrees(String hms) Converts a formatted hours:minutes:seconds string to an angle in degrees.
static double	polarDistanceDegrees(double ra1, double dec1, double radius1, double ra2, double dec2, double radius2) Calculates the distance in three dimensional space between two points specified in spherical polar coordinates.
static double	posAngDegrees(double ra1, double dec1, double ra2, double dec2) Calculates the position angle between two points on the sky in degrees.
static double	skyDistanceDegrees(double ra1, double dec1, double ra2, double dec2) Calculates the separation (distance around a great circle) of two points on the sky in degrees.

Methods inherited from class java.lang.Object

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

Method Detail

degreesToDms

public static String degreesToDms(double deg)

Converts an angle in degrees to a formatted degrees:minutes:seconds string. No fractional part of the seconds field is given.

Parameters:

deg - angle in degrees

Returns:

DMS-format string representing deg

degreesToDms

public static String degreesToDms(double deg,
                                  int secFig)

Converts an angle in degrees to a formatted degrees:minutes:seconds string with a given number of decimal places in the seconds field.

Parameters:

deg - angle in degrees

secFig - number of decimal places in the seconds field

Returns:

DMS-format string representing deg

degreesToHms

public static String degreesToHms(double deg)

Converts an angle in degrees to a formatted hours:minutes:seconds string. No fractional part of the seconds field is given.

Parameters:

deg - angle in degrees

Returns:

HMS-format string representing deg

degreesToHms

public static String degreesToHms(double deg,
                                  int secFig)

Converts an angle in degrees to a formatted hours:minutes:seconds string with a given number of decimal places in the seconds field.

Parameters:

deg - angle in degrees

secFig - number of decimal places in the seconds field

Returns:

HMS-format string representing deg

dmsToDegrees

public static double dmsToDegrees(String dms)

Converts a formatted degrees:minutes:seconds string to an angle in degrees. Delimiters may be colon, space, characters dm[s], or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.

Parameters:

dms - formatted DMS string

Returns:

angle in degrees specified by dms

Throws:

NumberFormatException - if dms can't be parsed as a degrees:minutes:seconds string

hmsToDegrees

public static double hmsToDegrees(String hms)

Converts a formatted hours:minutes:seconds string to an angle in degrees. Delimiters may be colon, space, characters hm[s], or some others. Additional spaces and leading +/- are permitted. The :seconds part is optional.

Parameters:

hms - formatted HMS string

Returns:

angle in degrees specified by hms

Throws:

NumberFormatException - if dms can't be parsed as an hours:minutes:seconds string

dmsToDegrees

public static double dmsToDegrees(double deg,
                                  double min,
                                  double sec)

Converts degrees, minutes, seconds to an angle in degrees.

In conversions of this type, one has to be careful to get the sign right in converting angles which are between 0 and -1 degrees. This routine uses the sign bit of the deg argument, taking care to distinguish between +0 and -0 (their internal representations are different for floating point values). It is illegal for the min or sec arguments to be negative.

Parameters:

deg - degrees part of angle

min - minutes part of angle

sec - seconds part of angle

Returns:

specified angle in degrees

Throws:

IllegalArgumentException - if an argument after the first non-zero one is negative

hmsToDegrees

public static double hmsToDegrees(double hour,
                                  double min,
                                  double sec)

Converts hours, minutes, seconds to an angle in degrees.

In conversions of this type, one has to be careful to get the sign right in converting angles which are between 0 and -1 hours. This routine uses the sign bit of the hour argument, taking care to distinguish between +0 and -0 (their internal representations are different for floating point values).

Parameters:

hour - degrees part of angle

min - minutes part of angle

sec - seconds part of angle

Returns:

specified angle in degrees

Throws:

IllegalArgumentException - if an argument after the first non-zero one is negative

skyDistanceDegrees

public static double skyDistanceDegrees(double ra1,
                                        double dec1,
                                        double ra2,
                                        double dec2)

Calculates the separation (distance around a great circle) of two points on the sky in degrees.

Parameters:

ra1 - right ascension of point 1 in degrees

dec1 - declination of point 1 in degrees

ra2 - right ascension of point 2 in degrees

dec2 - declination of point 2 in degrees

Returns:

angular distance between point 1 and point 2 in degrees

posAngDegrees

public static double posAngDegrees(double ra1,
                                   double dec1,
                                   double ra2,
                                   double dec2)

Calculates the position angle between two points on the sky in degrees. The result is in the range +/-180. If point 2 is due east of point 1, the result is +90. Zero is returned if the points are coincident.

Parameters:

ra1 - right ascension of point 1 in degrees

dec1 - declination of point 1 in degrees

ra2 - right ascension of point 2 in degrees

dec2 - declination of point 2 in degrees

Returns:

bearing in degrees of point 2 from point 1.

polarDistanceDegrees

public static double polarDistanceDegrees(double ra1,
                                          double dec1,
                                          double radius1,
                                          double ra2,
                                          double dec2,
                                          double radius2)

Calculates the distance in three dimensional space between two points specified in spherical polar coordinates.

Parameters:

ra1 - right ascension of point 1 in degrees

dec1 - declination of point1 in degrees

radius1 - distance from origin of point1

ra2 - right ascension of point 2 in degrees

dec2 - declination of point2 in degrees

radius2 - distance from origin of point2

Returns:

the linear distance between point1 and point2; units are as for radius1 and radius2