casacore
Nutation.h
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1//# Nutation.h: Nutation class
2//# Copyright (C) 1995,1996,1997,1998,2003,2004
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//#
27//# $Id$
28
29#ifndef MEASURES_NUTATION_H
30#define MEASURES_NUTATION_H
31
32//# Includes
33#include <casacore/casa/aips.h>
34#include <casacore/casa/Quanta/Quantum.h>
35#include <casacore/casa/Quanta/Euler.h>
36
37namespace casacore { //# NAMESPACE CASACORE - BEGIN
38
39//# Forward Declarations
40
41// <summary> Nutation class and calculations </summary>
42
43// <use visibility=export>
44
45// <reviewed reviewer="Tim Cornwell" date="1996/07/01" tests="tMeasMath"
46// demos="">
47// </reviewed>
48
49// <prerequisite>
50// <li> <linkto class=Measure>Measure</linkto> class
51// <li> <linkto class=Euler>Euler</linkto>
52// <li> <linkto class=MeasData>MeasData</linkto> class for constants
53// </prerequisite>
54//
55// <etymology>
56// Nutation
57// </etymology>
58//
59// <synopsis>
60// Nutation forms the class for Nutation calculations. It is a simple
61// container with the selected method, and the mean epoch.
62// It acts as a cache
63// for values and their derivatives, to enable fast calculations for time
64// epochs close together (see the <em>aipsrc</em> variable
65// <em>measures.nutation.d_interval</em>).
66//
67// The calculation method is selected from one of the following:
68// <ul>
69// <li> Nutation::STANDARD (at 1995/09/04 the IAU1980 definition,
70// from 2004/01/01 IAU2000B)
71// <li> Nutation::NONE (nutation of zero returned)
72// <li> Nutation::IAU1980
73// <li> Nutation::B1950
74// <li> Nutation::IAU2000
75// <li> Nutation::IAU2000A (equal to the full precision (uas) IAU2000)
76// <li> Nutation::IAU2000B (official lower precision (mas) of IAU2000)
77// </ul>
78// Epochs can be specified as the MJD (with defined constants MeasData::MJD2000
79// and MeasData::MJDB1950 or the actual MJD),
80// leading to the following constructors:
81// <ul>
82// <li> Nutation() default; assuming STANDARD
83// <li> Nutation(method)
84// </ul>
85// Actual Nutation for a certain Epoch is calculated by the () operator
86// as Nutation(epoch), with epoch Double MJD. Values are returned as an
87// <linkto class=Euler>Euler</linkto>.
88// The derivative (d<sup>-1</sup>) can be obtained as well by
89// derivative(epoch). <br>
90// A Nutation can be re-initialed with a different method and/or zero
91// epoch with the <src>init()</src> functions (same format as constructors).
92// To bypass the full calculation actual returned values are calculated
93// using the derivative if within about 2 hours (error less than about
94// 10<sup>-5</sup> mas). A call to refresh() will re-initiate calculations
95// from scratch.<br>
96// The following details can be set with the
97// <linkto class=Aipsrc>Aipsrc</linkto> mechanism:
98// <ul>
99// <li> measures.nutation.d_interval: approximation interval as time
100// (fraction of days is default unit) over which linear approximation
101// is used (default 0.04d (about 1 hour)).
102// <li> measures.nutation.b_usejpl: use the JPL database nutations for
103// IAU1980.
104// Else analytical expression, relative error about 10<sup>-9</sup>
105// Note that the JPL database to be used can be set with
106// measures.jpl.ephemeris (at the moment of writing DE200
107// (default), or DE405)
108// <li> measures.nutation.b_useiers: use the IERS Database nutation
109// corrections for IAU1980 (default False)
110// </ul>
111// </synopsis>
112//
113// <example>
114// <srcblock>
115// #include <casacore/measures/Measures.h>
116// MVDirection pos(Quantity(10,"degree"),Quantity(-10.5,"degree"));
117// // direction RA=10; DEC=-10.5
118// Nutation mine(Nutation::IAU1980); // define nutation type
119// RotMatrix rotat(mine(45837.0)); // rotation matrix for 84/05/17
120// MVDirection new = rotat*pos; // apply nutation
121// </srcblock>
122// The normal way to use Nutation is by using the
123// <linkto class=MeasConvert>MeasConvert</linkto> class.
124// </example>
125//
126// <motivation>
127// To calculate the Nutation angles. An alternate route could have been
128// a global function, but having a simple container allows caching of some
129// calculations for speed.<br>
130// Using MJD (JD-2400000.5) rather than JD is for precision reasons.
131// </motivation>
132//
133// <todo asof="2003/10/20">
134// <li> Correct deval_p (derivative complimentary eqox terms)
135// <li> Improve speed by a bit more lazyness in derivative calculations
136// and separate eqox calculations
137// </todo>
138
139class Nutation {
140 public:
141 //# Constants
142 // Interval to be used for linear approximation (in days)
143 static const Double INTV;
144
145 //# Enumerations
146 // Types of known Nutation calculations (at 1995/09/04 STANDARD == IAU1980,
147 // after 2004/01/01 it will be IAU2000B))
152
153 //# Constructors
154 // Default constructor, generates default J2000 Nutation identification
156 // Copy constructor
157 Nutation(const Nutation &other);
158 // Constructor with type
159 explicit Nutation(NutationTypes type);
160 // Copy assignment
162
163 //# Destructor
165
166 //# Operators
167 // Return the Nutation angles
168 const Euler &operator()(Double epoch);
169
170 //# General Member Functions
171 // Return derivative of Nutation (d<sup>-1</sup>)
172 const Euler &derivative(Double epoch);
173
174 // Re-initialise Nutation object
175 // <group>
176 void init();
177 void init(NutationTypes type);
178 // </group>
179
180 // Refresh calculations
181 void refresh();
182
183 // Get the equation of equinox
184 // <group>
187 Quantity getEqoxAngle(Double epoch, const Unit &unit) ;
188 // </group>
189 // Get the derivative of the equation of equinoxes in d<sup>-1</sup>
191 // Get the complimentary terms of the equation of equinoxes
193 // Get the derivative of the complimentary terms of the equation of equinoxes
195
196 private:
197
198 //# Data members
199 // Method to be used
201 // Check epoch for linear approximation
203 // Check epoch for calculation of derivatives
205 // Cached calculated angles
207 // Cached derivatives
209 // Cached equation of equinoxes
211 // Cached derivative equation of equinoxes
213 // Cached complimentary terms equation of equinoxes
215 // Cached derivative of complimentary terms equation of equinoxes
217 // To be able to use references rather than copies, and also to use these
218 // references in simple (up to 4 terms of Nutation results) expressions,
219 // results are calculated in circulating buffer
221 // Last calculation
223 // Interpolation interval
225 // IERS use
227 // JPL use
229 //# Member functions
230 // Make a copy
231 void copy(const Nutation &other);
232 // Fill an empty copy
233 void fill();
234 // Calculate Nutation angles for time t; also derivatives if True given
235 void calcNut(Double t, Bool calcDer = False);
236};
237
238
239} //# NAMESPACE CASACORE - END
240
241#endif
242
243
static uInt myInterval_reg
Interpolation interval.
Definition: Nutation.h:224
void init(NutationTypes type)
void calcNut(Double t, Bool calcDer=False)
Calculate Nutation angles for time t; also derivatives if True given.
Quantity getEqoxAngle(Double epoch)
Double neval_p
Cached complimentary terms equation of equinoxes.
Definition: Nutation.h:214
Nutation()
Default constructor, generates default J2000 Nutation identification.
NutationTypes
Types of known Nutation calculations (at 1995/09/04 STANDARD == IAU1980, after 2004/01/01 it will be ...
Definition: Nutation.h:148
Double nval_p[3]
Cached calculated angles.
Definition: Nutation.h:206
void refresh()
Refresh calculations.
Double eqoxCT(Double epoch)
Get the complimentary terms of the equation of equinoxes.
Double derivativeEqox(Double epoch)
Get the derivative of the equation of equinoxes in d-1
NutationTypes method_p
Method to be used.
Definition: Nutation.h:200
Euler result_p[4]
Last calculation.
Definition: Nutation.h:222
Double eqox(Double epoch)
Get the equation of equinox.
Nutation(NutationTypes type)
Constructor with type.
Quantity getEqoxAngle(Double epoch, const Unit &unit)
Nutation & operator=(const Nutation &other)
Copy assignment.
void fill()
Fill an empty copy.
static const Double INTV
Interval to be used for linear approximation (in days)
Definition: Nutation.h:143
Double deval_p
Cached derivative of complimentary terms equation of equinoxes.
Definition: Nutation.h:216
Double checkDerEpoch_p
Check epoch for calculation of derivatives.
Definition: Nutation.h:204
Double checkEpoch_p
Check epoch for linear approximation.
Definition: Nutation.h:202
void init()
Re-initialise Nutation object.
Nutation(const Nutation &other)
Copy constructor.
const Euler & derivative(Double epoch)
Return derivative of Nutation (d-1)
static uInt myUseiers_reg
IERS use.
Definition: Nutation.h:226
Int lres_p
To be able to use references rather than copies, and also to use these references in simple (up to 4 ...
Definition: Nutation.h:220
static uInt myUsejpl_reg
JPL use.
Definition: Nutation.h:228
Double eqeq_p
Cached equation of equinoxes.
Definition: Nutation.h:210
const Euler & operator()(Double epoch)
Return the Nutation angles.
Double dval_p[3]
Cached derivatives.
Definition: Nutation.h:208
Double derivativeEqoxCT(Double epoch)
Get the derivative of the complimentary terms of the equation of equinoxes.
void copy(const Nutation &other)
Make a copy.
Double deqeq_p
Cached derivative equation of equinoxes.
Definition: Nutation.h:212
this file contains all the compiler specific defines
Definition: mainpage.dox:28
const Bool False
Definition: aipstype.h:44
unsigned int uInt
Definition: aipstype.h:51
int Int
Definition: aipstype.h:50
bool Bool
Define the standard types used by Casacore.
Definition: aipstype.h:42
double Double
Definition: aipstype.h:55