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00001 //# Stokes.h: Stokes parameter definitions for interface to table data 00002 //# Copyright (C) 1994,1995,1996,1997,2000 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: Stokes.h 18093 2004-11-30 17:51:10Z ddebonis $ 00027 00028 #ifndef MEASURES_STOKES_H 00029 #define MEASURES_STOKES_H 00030 00031 #include <casa/aips.h> 00032 #include <casa/BasicSL/String.h> 00033 #include <casa/Utilities/Fallible.h> 00034 00035 00036 namespace casa { //# NAMESPACE CASA - BEGIN 00037 00038 // <summary> 00039 // Stokes parameter definitions for interface to table data. 00040 // </summary> 00041 00042 // <reviewed tests="tStokes"> 00043 // </reviewed> 00044 00045 // <synopsis> 00046 // This enumerates the available Stokes types, but does not define 00047 // the operations for conversion between Stokes types. 00048 // This class is a wrapper for the ENUM and conversion functions. 00049 // </synopsis> 00050 00051 class Stokes { 00052 public: 00053 00054 // The Stokes types are defined by this enum. 00055 // 00056 // <note role=warning> 00057 // <b>DO NOT CHANGE THE ORDER OF THESE TYPES</b>, as the integers corresponding 00058 // to the <src>enum</src> are required for storage in Tables. 00059 // One can add to these types, but the order must be preserved. 00060 // The correlation products are required to have the order indicated with 00061 // values of 1,2,3,4 plus n*4. 00062 // </note> 00063 // 00064 //# The enum comments below are placed in the position they are to make the 00065 //# extracted documentation look nice. 00066 enum StokesTypes { 00067 // undefined value = 0 00068 Undefined=0, 00069 I, 00070 Q, 00071 U, 00072 // standard stokes parameters 00073 V, 00074 // 00075 RR, 00076 RL, 00077 LR, 00078 // circular correlation products 00079 LL, 00080 // 00081 XX, 00082 XY, 00083 YX, 00084 // linear correlation products 00085 YY, 00086 // 00087 RX, 00088 RY, 00089 LX, 00090 LY, 00091 XR, 00092 XL, 00093 YR, 00094 // mixed correlation products 00095 YL, 00096 // 00097 PP, 00098 PQ, 00099 QP, 00100 // general quasi-orthogonal correlation products 00101 QQ, 00102 // 00103 RCircular, 00104 LCircular, 00105 // single dish polarization types 00106 Linear, 00107 // Polarized intensity ((Q^2+U^2+V^2)^(1/2)) 00108 Ptotal, 00109 // Linearly Polarized intensity ((Q^2+U^2)^(1/2)) 00110 Plinear, 00111 // Polarization Fraction (Ptotal/I) 00112 PFtotal, 00113 // Linear Polarization Fraction (Plinear/I) 00114 PFlinear, 00115 // Linear Polarization Angle (0.5 arctan(U/Q)) (in radians) 00116 Pangle 00117 }; 00118 00119 // The number of StokesTypes. 00120 // <note role=warning> 00121 // <b>Update</b> <src>NumberOfTypes</src> when entries are added. 00122 // </note> 00123 enum { 00124 // The number of StokesTypes. 00125 NumberOfTypes = 33 00126 }; 00127 00128 // convert Int to StokesTypes, returns Stokes::Undefined if 00129 // it is an invalid type 00130 static StokesTypes type(Int stokesNumber); 00131 00132 // convert String to StokesTypes, returns Stokes::Undefined if 00133 // it is an unrecognized string. The valid strings are the 00134 // same as the characters used in the enum above (i.e. 00135 // "I" returns Stokes::I, "Linear" returns Stokes::Linear, etc). 00136 static StokesTypes type(const String & stokesName); 00137 00138 // convert StokesTypes to String, Stokes::Undefined returns 00139 // "??". 00140 static String name(StokesTypes stokesType); 00141 00142 00143 00144 // map StokesTypes to receptor number (0 or 1) for the 00145 // interferometric correlation products. 00146 // e.g. XY will give receptor1==0 receptor2==1 etc. 00147 // I,Q,U,V and the single dish types will produce invalid 00148 // Fallible. 00149 // <group> 00150 static Fallible<Int> receptor1(StokesTypes stokesType); 00151 static Fallible<Int> receptor2(StokesTypes stokesType); 00152 // </group> 00153 00154 // These two functions map stokes type to FITS type and vice versa. If you add a 00155 // StokesType you should change these functions as well. 00156 // <ul> 00157 // <li> I,Q,U,V <-> 1,2,3,4 00158 // <li> RR,LL,RL,LR <-> -1,-2,-3,-4 Note! Not the same as enum order! 00159 // <li> XX,YY,XY,YX <-> -5,-6,-7,-8 Note! Not the same as enum order! 00160 // <li> Otherwise, FITS type <-> 100 + Int(stokesType). This is not standard FITS. 00161 // </ul> 00162 // <group> 00163 static Int FITSValue(StokesTypes which); 00164 static StokesTypes fromFITSValue(Int); 00165 // </group> 00166 private: 00167 }; 00168 00169 00170 } //# NAMESPACE CASA - END 00171 00172 #endif 00173