casa
$Rev:20696$
|
00001 //# ConstantSpectrum.h: Model the spectral variation with a constant 00002 //# Copyright (C) 1998,1999,2000,2003 00003 //# Associated Universities, Inc. Washington DC, USA. 00004 //# 00005 //# This library is free software; you can redistribute it and/or modify it 00006 //# under the terms of the GNU Library General Public License as published by 00007 //# the Free Software Foundation; either version 2 of the License, or (at your 00008 //# option) any later version. 00009 //# 00010 //# This library is distributed in the hope that it will be useful, but WITHOUT 00011 //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00012 //# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public 00013 //# License for more details. 00014 //# 00015 //# You should have received a copy of the GNU Library General Public License 00016 //# along with this library; if not, write to the Free Software Foundation, 00017 //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA. 00018 //# 00019 //# Correspondence concerning AIPS++ should be addressed as follows: 00020 //# Internet email: aips2-request@nrao.edu. 00021 //# Postal address: AIPS++ Project Office 00022 //# National Radio Astronomy Observatory 00023 //# 520 Edgemont Road 00024 //# Charlottesville, VA 22903-2475 USA 00025 //# 00026 //# $Id: ConstantSpectrum.h 18093 2004-11-30 17:51:10Z ddebonis $ 00027 00028 #ifndef COMPONENTS_CONSTANTSPECTRUM_H 00029 #define COMPONENTS_CONSTANTSPECTRUM_H 00030 00031 #include <casa/aips.h> 00032 #include <components/ComponentModels/ComponentType.h> 00033 #include <components/ComponentModels/SpectralModel.h> 00034 00035 namespace casa { //# NAMESPACE CASA - BEGIN 00036 00037 class MFrequency; 00038 class RecordInterface; 00039 class String; 00040 template <class T> class Vector; 00041 00042 // <summary>Model the spectral variation with a constant</summary> 00043 00044 // <use visibility=export> 00045 00046 // <reviewed reviewer="" date="yyyy/mm/dd" tests="tConstantSpectrum" demos="dConstantSpectrum"> 00047 // </reviewed> 00048 00049 // <prerequisite> 00050 // <li> <linkto class="SpectralModel">SpectralModel</linkto> 00051 // </prerequisite> 00052 // 00053 // <synopsis> 00054 00055 // This class models the spectral variation of a component as constant, 00056 // ie. unchanging with frequency. It is the simplest possible model for 00057 // spectral variation. 00058 00059 // This class like the other spectral models becomes more useful when used 00060 // through the <linkto class=SkyComponent>SkyComponent</linkto> class, which 00061 // incorperates the flux and spatial variation of the emission, or through the 00062 // <linkto class=ComponentList>ComponentList</linkto> class, which handles 00063 // groups of SkyComponent objects. 00064 00065 // Because the flux is constant with frequency the concept of a reference 00066 // frequency is meaningless with this class. But it can still be accessed using 00067 // the <src>refFrequency</src> and <src>setRefFrequency</src>. However changing 00068 // its value will not affect the behaviour of this class. 00069 00070 // This class does not have any parameters and the <src>nParameters</src> 00071 // function will return zero. It is an error that will generate an exception 00072 // (in Debug mode) to call the <src>setParameters</src> and 00073 // <src>parameters</src> functions with anything other than a zero length 00074 // vector. 00075 00076 // The <src>sample</src> functions always return 1.0. 00077 00078 // This class also contains functions (<src>toRecord</src> & 00079 // <src>fromRecord</src>) which perform the conversion between Records and 00080 // ConstantSpectrum objects. These functions define how a ConstantSpectrum 00081 // object is represented in glish. The format of the record that is generated 00082 // and accepted by these functions is: 00083 // <srcblock> 00084 // c := [type = 'constant', 00085 // frequency = [type = 'frequency', 00086 // refer = 'lsr', 00087 // m0 = [value = 1, unit = 'GHz'] 00088 // ] 00089 // ] 00090 // </srcblock> 00091 // The frequency field contains a record representation of a frequency measure 00092 // and its format is defined in the Measures module. Its refer field defines 00093 // the reference frame for the direction and the m0 field defines the value of 00094 // the reference frequency. The parsing of the type field is case 00095 // insensitive. 00096 // </synopsis> 00097 00098 // <example> 00099 // Its hard to think of a good example for this class as it is basically does 00100 // nothing! In this example the spectral variation of a component is set to to 00101 // a constant value. 00102 // <srcblock> 00103 // SkyComponent myComp(...); 00104 // ... 00105 // if (myComp.spectrum().type() != ComponentType::CONSTANT_SPECTRUM) { 00106 // myComp.spectrum() = ConstantSpectrum(); 00107 // } 00108 // </srcblock> 00109 // </example> 00110 // 00111 // <motivation> 00112 // A ConstantSpectrum class is needed for users who are not interested in 00113 // modelling any spectral variation in their components. 00114 // </motivation> 00115 // 00116 // <todo asof="1999/11/23"> 00117 // <li> Nothing I hope! 00118 // </todo> 00119 00120 // <linkfrom anchor="ConstantSpectrum" classes="SpectralModel SpectralIndex"> 00121 // <here>ConstantSpectrum</here> - Models the spectrum as constant 00122 // </linkfrom> 00123 00124 class ConstantSpectrum: public SpectralModel 00125 { 00126 public: 00127 // The default constructor is the only one you really need as this class has 00128 // no parameters! 00129 ConstantSpectrum(); 00130 00131 // The copy constructor uses copy semantics 00132 ConstantSpectrum(const ConstantSpectrum& other); 00133 00134 // The destructor does nothing. 00135 virtual ~ConstantSpectrum(); 00136 00137 // The assignment operator uses copy semantics. 00138 ConstantSpectrum& operator=(const ConstantSpectrum& other); 00139 00140 // return the actual spectral type. This function always returns 00141 // ComponentType::CONSTANT_SPECTRUM 00142 virtual ComponentType::SpectralShape type() const; 00143 00144 // Return the scaling factor that indicates the flux is at the specified 00145 // frequency assuming the flux at the reference frequency is one. This 00146 // function always returns one, as the spectrum is constant. 00147 virtual Double sample(const MFrequency& centerFrequency) const; 00148 00149 // Same as the previous function except that many frequencies can be sampled 00150 // at once. The reference frame must be the same for all the specified 00151 // frequencies. Uses a customised implementation. 00152 virtual void sample(Vector<Double>& scale, 00153 const Vector<MFrequency::MVType>& frequencies, 00154 const MFrequency::Ref& refFrame) const; 00155 00156 // Return a pointer to a copy of this object upcast to a SpectralModel 00157 // object. The class that uses this function is responsible for deleting the 00158 // pointer. This is used to implement a virtual copy constructor. 00159 virtual SpectralModel* clone() const; 00160 00161 // return the number of parameters. There are no parameters for this spectral 00162 // model. So calling <src>setParameters</src> or <src>parameters</src> with 00163 // anything other than a zero length Vector will throw an exception (when 00164 // compiled in debug mode). 00165 // <group> 00166 virtual uInt nParameters() const; 00167 virtual void setParameters(const Vector<Double>& newSpectralParms); 00168 virtual Vector<Double> parameters() const; 00169 virtual void setErrors(const Vector<Double>& newSpectralErrs); 00170 virtual Vector<Double> errors() const; 00171 // </group> 00172 00173 // These functions convert between a Record and a ConstantSpectrum. These 00174 // functions define how a ConstantSpectrum object is represented in glish and 00175 // this is detailed in the synopsis above. These functions return False if 00176 // the record is malformed and append an error message to the supplied string 00177 // giving the reason. 00178 // <group> 00179 virtual Bool fromRecord(String& errorMessage, 00180 const RecordInterface& record); 00181 virtual Bool toRecord(String& errorMessage, RecordInterface& record) const; 00182 // </group> 00183 00184 // Convert the parameters of the spectrum to the specified units. As a 00185 // constant spectrum has no parameters this function does nothing and always 00186 // returns True. 00187 virtual Bool convertUnit(String& errorMessage, 00188 const RecordInterface& record); 00189 00190 // Function which checks the internal data of this class for consistant 00191 // values. Returns True if everything is fine otherwise returns False. 00192 virtual Bool ok() const; 00193 }; 00194 00195 } //# NAMESPACE CASA - END 00196 00197 #endif