Astro::Coords::Angle - Representation of an angle
use Astro::Coords::Angle; $ang = new Astro::Coords::Angle( 45.5, units => 'deg' ); $ang = new Astro::Coords::Angle( "45:30:00", units => 'sexagesimal' ); $rad = $ang->radians; $deg = $ang->degrees; $asec = $ang->arcsec; $amin = $ang->arcmin; $string = $ang->string;
Helper class for
Astro::Coords to represent an angle. Methods are provided for parsing angles in sexagesimal format and for returning angles in any desired format.
Construct a new
Angle object. Must be called with an angle as first argument. Optional hash arguments can be supplied to specify, for example, the units of the supplied angle.
$ang = new Astro::Coords::Angle( $angle, units => "degrees" );
Supported options are:
units - units of the supplied string or number range - restricted range of the angle
Supported units are:
sexagesimal - A string of format either dd:mm:ss or "dd mm ss" "dms" separators are also supported. degrees - decimal degrees radians - radians arcsec - arc seconds (abbreviated form is 'as') arcmin - arc minutes (abbreviated form is 'am')
The units can be abbreviated to the first 3 characters.
If the units are not supplied the default is to assume "sexagesimal" if the supplied string contains spaces or colons or the characters "d", "m" or "s", "degrees" if the supplied number is greater than 2*PI (6.28), and "radians" for all other values. Negative angles are supported.
The options for range are documented in the
If the angle can not be decoded (if a string), the constructor will fail.
Return the angle in radians.
$rad = $ang->radians;
Return the angle in decimal degrees.
$deg = $ang->degrees;
Number of decimal places to use when stringifying the object. Default is to use the global class value (see the
NDP class method). Set to
undef to revert to the class setting.
$ang->str_ndp( 4 ); $ndp = $ang->str_ndp;
Delimiter to use between components when stringifying. Default is to use the global class value (see the
DELIM class method). Set to
undef to revert to the class setting.
$ang->str_delim( ":" ); $delim = $ang->str_delim;
Return an array of components that correspond to the sign, degrees, arcminutes and arcseconds of the angle. The sign will be either a '+' or '-' and is required to distinguish '+0' from '-0'.
@comp = $ang->components;
The number of decimal places in the seconds will not be constrained by the setting of
str_ndp, but is constrained by an optional argument:
@comp = $ang->components( $ndp );
Default resolution is 5 decimal places.
In scalar context, returns a reference to an array.
Return the angle as a string in sexagesimal format (e.g. 12:30:52.4).
$string = $ang->string();
The form of this string depends on the
str_ndp settings and on whether the angular range allows negative values (the sign will be dropped if the range is known to be positive).
Return the angle in arcseconds.
$asec = $ang->arcsec;
Return the angle in arcminutes.
$amin = $ang->arcmin;
String describing the allowed range of the angle. Allowed values are
NONE - no pre-determined range 2PI - 0 to 2*PI radians (0 to 360 degrees) PI - -PI to +PI radians (-180 to 180 degrees)
Any other strings will be ignored (and a warning issued if appropriate).
When a new value is provided, the angle is normalised to this range. Note that this is not always reversible (especially if reverting to "NONE"). The range can also be specified to the constructor.
Default is not to normalize the angle.
Simple wrapper method to support the backwards compatibility interface in
Astro::Coords when requesting an angle by using a string format rather than an explicit method.
$angle = $ang->in_format( 'sexagesimal' );
Supported formats are:
radians calls 'radians' method degrees calls 'degrees' method sexagesimal calls 'string' method array calls 'components' method (returns 2 dp resolution) arcsec calls 'arcsec' method arcmin calls 'arcmin' method
The format can be abbreviated to the first 3 letters, or 'am' or 'as' for arcmin and arcsec respectively. If no format is specified explicitly, the object itself will be returned.
Create new cloned copy of this object.
$clone = $ang->clone;
Negate the sense of the angle, returning a new angle object.
$neg = $ang->negate;
Not allowed if the range is defined as 0 to 2PI.
The object is overloaded such that it stringifies via the
string method, and returns the angle in radians in numify context.
The following methods control the default behaviour of the class.
The number of decimal places to use in the fractional part of the number when stringifying (from either the
string method or the
Astro::Coords::Angle->NDP( 4 );
Default value is 2. If this is changed then all instances will be affected on stringification unless the
str_ndp attribute has been set explicitly for an instance.
If an undefined argument is supplied, the class will revert to its initial state.
Astro::Coords::Angle->NDP( undef );
Delimiter to use to separate components of a sexagesimal triplet when the object is stringified. If this is changed then all instances will be affected on stringification unless the
str_delim attribute has been set explicitly for an instance.
Common values are a colon (12:52:45.4) or a space (12 52 45.4). If more than one character is present in the string, each character will be used in turn as a delimiter in the string until either no more gaps are present (or characters have been exhausted. In the former, if there are more characters than gaps, the first character remaining in the string will be appended, in the latter case, no more characters will be printed. For example, "dms" would result in '12d52m45.4s', whereas 'dm' would result in '12d52m45.4'
Astro::Coords::Angle->DELIM( ':' );
Default is ":". An undefined argument will result in the class reverting to the default state.
Low level utility routine to convert an input value in specified format to radians. This method uses the same code as the object constructor to parse the supplied input argument but does not require the overhead of object construction if the result is only to be used transiently.
$rad = Astro::Coords::Angle->to_radians( $string, $format );
See the constructor documentation for the supported format strings.
Tim Jenness <firstname.lastname@example.org>
Copyright (C) 2004-2005 Tim Jenness. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
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