Base for Reference frame for physical measures. More...

#include <MRBase.h>

Inheritance diagram for casa::MRBase:

Public Member Functions
virtual	~MRBase ()
virtual Bool	empty () const =0
	Check if empty reference.
virtual uInt	getType () const =0
	Check the type of Measure the reference can be used for: `static const String &showMe() = 0;` .
virtual MeasFrame &	getFrame ()=0
	Return the frame of the reference.
virtual const Measure *	offset () const =0
	Return the first frame which has specified information.
virtual void	setType (uInt tp)=0
	Set the type.
virtual void	set (uInt tp)=0
virtual void	set (const MeasFrame &mf)=0
	Set a new offset: void set(const Measure &ep); Set a new frame.
virtual void	print (ostream &os) const =0
	Print a Measure.
Friends
ostream &	operator<< (ostream &os, const MRBase &meas)

Detailed Description

Base for Reference frame for physical measures.

Intended use:

Internal

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: tMeasure

Prerequisite

Quantum class
Measure class

Etymology

From Measure and Reference and Base

Synopsis

MRBase is the abstract base class for reference frames. Reference frames are specified (see Measure ) as Measure::Ref (e.g. MEpoch::Ref).

A Measure::Ref is a container for type indicators, (e.g. MDirection::J2000), an optional offset (e.g. beginning of year), and, if necessary, a MeasFrame .
A MeasFrame consists of one or more Measures specifying the reference frame (e.g. an MPosition for a sidereal time definition). A time ( MEpoch ) could e.g. have a type MEpoch::TAI, and an MEpoch as offset:

    MEpoch off(Quantity(40745,"d"), MEpoch::Ref(MEpoch::UTC));
    MEpoch::Ref myref(MEpoch::TAI, off);

It is obvious that a circular reference between Measure and Measure::Ref is possible. Therefore, each Measure has a default reference (necessary anyway to be able to start a Measure chain). For MEpoch the default is e.g. an MJD in UTC; and the default Measure for an MEpoch reference is 0.
References are copied by reference; i.e. a reference can be used in many places without overhead.
Some Measure::Ref could need additional conversion information ( example: type of Nutation calculations). They are provided by Aipsrc keywords.
All constructors are related to a specific Measure, to be able to check relations at compile time.

Example

See Measure for an example

Motivation

To gather all reference frame information in the one class.

Definition at line 103 of file MRBase.h.

Constructor & Destructor Documentation

virtual casa::MRBase::~MRBase ( ) [virtual]

Member Function Documentation

virtual Bool casa::MRBase::empty ( ) const [pure virtual]

Check if empty reference.

Implemented in casa::MeasRef< Ms >, casa::MeasRef< MRadialVelocity >, casa::MeasRef< MBaseline >, casa::MeasRef< MDirection >, casa::MeasRef< MPosition >, casa::MeasRef< MFrequency >, casa::MeasRef< Muvw >, casa::MeasRef< MEarthMagnetic >, casa::MeasRef< MDoppler >, casa::MeasRef< MEpoch >, and casa::MeasRef< M >.

virtual MeasFrame& casa::MRBase::getFrame ( ) [pure virtual]

Return the frame of the reference.

Implemented in casa::MeasRef< Ms >, casa::MeasRef< MRadialVelocity >, casa::MeasRef< MBaseline >, casa::MeasRef< MDirection >, casa::MeasRef< MPosition >, casa::MeasRef< MFrequency >, casa::MeasRef< Muvw >, casa::MeasRef< MEarthMagnetic >, casa::MeasRef< MDoppler >, casa::MeasRef< MEpoch >, and casa::MeasRef< M >.

virtual uInt casa::MRBase::getType ( ) const [pure virtual]

Check the type of Measure the reference can be used for:
static const String &showMe() = 0; .

Return the type of the reference
Caution: the following should really be (and should be interpreted as), but compiler does not accept it:
Ms::Types getType();

Implemented in casa::MeasRef< Ms >, casa::MeasRef< MRadialVelocity >, casa::MeasRef< MBaseline >, casa::MeasRef< MDirection >, casa::MeasRef< MPosition >, casa::MeasRef< MFrequency >, casa::MeasRef< Muvw >, casa::MeasRef< MEarthMagnetic >, casa::MeasRef< MDoppler >, casa::MeasRef< MEpoch >, and casa::MeasRef< M >.

virtual const Measure* casa::MRBase::offset ( ) const [pure virtual]

Return the first frame which has specified information.

Checking is done in argument order.

Thrown Exceptions

AipsError if neither reference has a frame or the proper type

       static const MeasFrame &framePosition(const MRBase &ref1,
                                                const MRBase &ref2) = 0;
       static const MeasFrame &frameEpoch(const MRBase &ref1,
                                         const MRBase &ref2) = 0;
       static const MeasFrame &frameDirection(const MRBase &ref1,
                                             const MRBase &ref2) = 0;
       static const MeasFrame &frameRadialVelocity(const MRBase &ref1,
                                                  const MRBase &ref2) = 0;