File: polarization.h

package info (click to toggle)
wsclean 2.8-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, sid
  • size: 2,196 kB
  • sloc: cpp: 34,504; ansic: 234; python: 174; makefile: 10
file content (386 lines) | stat: -rw-r--r-- 11,269 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
#ifndef POLARIZATION_H
#define POLARIZATION_H

#include <complex>
#include <stdexcept>
#include <set>
#include <vector>

/**
 * Class for various simple polarization related values.
 * 
 * The visibility relations for converting polarizations are:
 * 
 *   RR = I + V  ;   I = (RR + LL)/2
 *   RL = Q + iU ;   Q = (RL + LR)/2
 *   LR = Q - iU ;   U = -i (RL - LR)/2
 *   LL = I - V  ;   V = (RR - LL)/2
 *
 *   XX = I + Q  ;   I = (XX + YY)/2
 *   XY = U + iV ;   Q = (XX - YY)/2
 *   YX = U - iV ;   U = (XY + YX)/2
 *   YY = I - Q  ;   V = -i(XY - YX)/2
 * 
 * These definitions assume that 'X' and 'Y' are labelled as they are in
 * CASA measurement sets: X is North-South.
 * 
 * Note that uv-fits files have the polarizations labelled such that X
 * is East-West, confusingly. We have also observed that at present (2016)
 * CASA's importuvfits does not swap the polarizations, hence Measurement
 * Sets exist that have the polarizations labelled wrong.
 * The IEEE definition is to have X be N-S.
 */
class Polarization
{
public:
	enum PolarizationEnum
	{
		StokesI,
		StokesQ,
		StokesU,
		StokesV,
		RR,
		RL,
		LR,
		LL,
		XX,
		XY,
		YX,
		YY,
		/**
		 * Instrumental is a special value representing that four polarizations are
		 * stored, and these are the 'raw' measurement set polarizations. It is used
		 * as a special value that e.g. can be passed to a MSProvider, which would mean
		 * all values are gridded at once, as required for an a-term correcting gridder.
		 */
		Instrumental
	};
	
	static size_t TypeToIndex(enum PolarizationEnum polarization, size_t polCountInSet)
	{
		switch(polCountInSet)
		{
			case 1:
				if(polarization != StokesI)
					throw std::runtime_error("TypeTo4PolIndex(): can't convert given polarization to index");
				else
					return 0;
			case 2:
			switch(polarization)
			{
				case XX: return 0;
				case YY: return 1;
				default: throw std::runtime_error("TypeTo4PolIndex(): can't convert given polarization to index");
			}
			case 4:
			switch(polarization)
			{
				case XX: return 0;
				case XY: return 1;
				case YX: return 2;
				case YY: return 3;
				default: throw std::runtime_error("TypeTo4PolIndex(): can't convert given polarization to index");
			}
			default: throw std::runtime_error("TypeTo4PolIndex(): can't convert given polarization to index");
		}
	}
	
	static enum PolarizationEnum AipsIndexToEnum(int index)
	{
		switch(index)
		{
			case 1: return StokesI;
			case 2: return StokesQ;
			case 3: return StokesU;
			case 4: return StokesV;
			case 5: return RR;
			case 6: return RL;
			case 7: return LR;
			case 8: return LL;
			case 9: return XX;
			case 10: return XY;
			case 11: return YX;
			case 12: return YY;
			default: throw std::runtime_error("AipsIndexToEnum(): unknown aips polarization index");
		}
	}
	
	static bool TypeToIndex(enum PolarizationEnum polarization, const std::vector<PolarizationEnum>& polList, size_t& index)
	{
		for(size_t i=0; i!=polList.size(); ++i)
		{
			if(polList[i] == polarization)
			{
				index = i;
				return true;
			}
		}
		return false;
	}
	
	template<typename Range>
	static bool TypeToIndex(enum PolarizationEnum polarization, const Range& polList, size_t& index)
	{
		size_t curIndex = 0;
		for(typename Range::const_iterator i=polList.begin(); i!=polList.end(); ++i, ++curIndex)
		{
			if(*i == polarization)
			{
				index = curIndex;
				return true;
			}
		}
		return false;
	}
	
	static size_t StokesToIndex(enum PolarizationEnum polarization)
	{
		switch(polarization)
		{
			default:
			case StokesI: return 0;
			case StokesQ: return 1;
			case StokesU: return 2;
			case StokesV: return 3;
		}
	}
	
	static PolarizationEnum IndexToStokes(size_t index)
	{
		const static PolarizationEnum arr[4] = { StokesI, StokesQ, StokesU, StokesV };
		return arr[index];
	}
	
	static bool IsStokes(enum PolarizationEnum polarization)
	{
		return
			polarization == StokesI || polarization == StokesQ ||
			polarization == StokesU || polarization == StokesV;
	}
	
	static size_t TypeTo4PolIndex(enum PolarizationEnum polarization)
	{
		switch(polarization)
		{
			case XX: return 0;
			case XY: return 1;
			case YX: return 2;
			case YY: return 3;
			default: throw std::runtime_error("TypeTo4PolIndex(): can't convert given polarization to index");
		}
	}
	
	static std::string TypeToShortString(enum PolarizationEnum polarization)
	{
		switch(polarization)
		{
			case XX: return "XX";
			case XY: return "XY";
			case YX: return "YX";
			case YY: return "YY";
			case StokesI: return "I";
			case StokesQ: return "Q";
			case StokesU: return "U";
			case StokesV: return "V";
			case RR: return "RR";
			case RL: return "RL";
			case LR: return "LR";
			case LL: return "LL";
			case Instrumental: return "instr";
			default: return "";
		}
	}
	
	static std::string TypeToFullString(enum PolarizationEnum polarization)
	{
		switch(polarization)
		{
			case XX: return "XX";
			case XY: return "XY";
			case YX: return "YX";
			case YY: return "YY";
			case StokesI: return "Stokes I";
			case StokesQ: return "Stokes Q";
			case StokesU: return "Stokes U";
			case StokesV: return "Stokes V";
			case RR: return "RR";
			case RL: return "RL";
			case LR: return "LR";
			case LL: return "LL";
			case Instrumental: return "instrumental";
			default: return "Unknown polarization";
		}
	}
	
	static bool HasFullPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return
			HasFullLinearPolarization(polarizations) || HasFullStokesPolarization(polarizations)
			||
			(polarizations.count(RR)>0 && polarizations.count(RL)>0 &&
			 polarizations.count(LR)>0 && polarizations.count(LL)>0);
	}
	
	static bool HasFullLinearPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return
			(polarizations.count(XX)>0 && polarizations.count(XY)>0 &&
			 polarizations.count(YX)>0 && polarizations.count(YY)>0);
	}
	
	static bool HasFullCircularPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return
			(polarizations.count(LL)>0 && polarizations.count(LR)>0 &&
			 polarizations.count(RL)>0 && polarizations.count(RR)>0);
	}
	
	static bool HasFullStokesPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return
			(polarizations.count(StokesI)>0 && polarizations.count(StokesQ)>0 &&
			 polarizations.count(StokesU)>0 && polarizations.count(StokesV)>0);
	}
	
	static bool HasDualPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return HasDualLinearPolarization(polarizations) ||
			(polarizations.count(RR)>0 && polarizations.count(LL)>0);
	}
	
	static bool HasDualLinearPolarization(const std::set<PolarizationEnum>& polarizations)
	{
		return (polarizations.count(XX)>0 && polarizations.count(YY)>0);
	}
	
	static bool IsComplex(PolarizationEnum polarization)
	{
		return polarization==XY || polarization==YX;
	}
	
	static PolarizationEnum ParseString(const std::string& str)
	{
		if(str == "XX") return XX;
		else if(str == "XY") return XY;
		else if(str == "YX") return YX;
		else if(str == "YY") return YY;
		else if(str == "I") return StokesI;
		else if(str == "Q") return StokesQ;
		else if(str == "U") return StokesU;
		else if(str == "V") return StokesV;
		else if(str == "RR") return RR;
		else if(str == "RL") return RL;
		else if(str == "LR") return LR;
		else if(str == "LL") return LL;
		else throw std::runtime_error(std::string("Could not parse polarization string: ") + str);
	}
	
	static std::set<PolarizationEnum> ParseList(const std::string& listStr)
	{
		std::set<PolarizationEnum> list;
		enum { StartSt, GotXSt, GotYSt, GotLSt, GotRSt, GotSeperatorSt } state = StartSt;
		for(std::string::const_iterator i=listStr.begin(); i!=listStr.end(); ++i)
		{
			char c = (*i>='a' && *i<='z') ? *i-('a'-'A') : *i;
			switch(c)
			{
				case 'X':
					if(state == StartSt || state == GotSeperatorSt) state=GotXSt;
					else {
						if(state==GotXSt) list.insert(XX);
						else if(state==GotYSt) list.insert(YX);
						else throw std::runtime_error("Invalid polarization list: parse error near 'X'");
						state=StartSt;
					}
					break;
				case 'Y':
					if(state == StartSt || state == GotSeperatorSt) state=GotYSt;
					else {
						if(state==GotXSt) list.insert(XY);
						else if(state==GotYSt) list.insert(YY);
						else throw std::runtime_error("Invalid polarization list: parse error near 'Y'");
						state=StartSt;
					}
					break;
				case 'R':
					if(state == StartSt || state == GotSeperatorSt) state=GotRSt;
					else {
						if(state==GotRSt) list.insert(RR);
						else if(state==GotLSt) list.insert(LR);
						else throw std::runtime_error("Invalid polarization list: parse error near 'R'");
						state=StartSt;
					}
					break;
				case 'L':
					if(state == StartSt || state == GotSeperatorSt) state=GotLSt;
					else {
						if(state==GotRSt) list.insert(RL);
						else if(state==GotLSt) list.insert(LL);
						else throw std::runtime_error("Invalid polarization list: parse error near 'L'");
						state=StartSt;
					}
					break;
				case 'I':
					if(state == StartSt || state == GotSeperatorSt) list.insert(StokesI);
					else throw std::runtime_error("Invalid polarization list: parse error near 'I'");
					state = StartSt;
					break;
				case 'Q':
					if(state == StartSt || state == GotSeperatorSt) list.insert(StokesQ);
					else throw std::runtime_error("Invalid polarization list: parse error near 'Q'");
					state = StartSt;
					break;
				case 'U':
					if(state == StartSt || state == GotSeperatorSt) list.insert(StokesU);
					else throw std::runtime_error("Invalid polarization list: parse error near 'U'");
					state = StartSt;
					break;
				case 'V':
					if(state == StartSt || state == GotSeperatorSt) list.insert(StokesV);
					else throw std::runtime_error("Invalid polarization list: parse error near 'V'");
					state = StartSt;
					break;
				case ',':
				case ' ':
				case '/':
					if(state == StartSt) state = GotSeperatorSt;
					else throw std::runtime_error("Invalid polarization list: parse error near seperator");
			}
		}
		if(state!=StartSt)
			throw std::runtime_error("Invalid polarization list: parse error near string end");
		return list;
	}
	
	template<typename NumType>
	static void LinearToStokes(const std::complex<NumType> *linear, NumType* stokes)
	{
		// Note comments about X and Y at the top of this file!
		stokes[0] = 0.5 * (linear[0].real() + linear[3].real());
		stokes[1] = 0.5 * (linear[0].real() - linear[3].real());
		stokes[2] = 0.5 * (linear[1].real() + linear[2].real());
		stokes[3] = 0.5 * (linear[1].imag() - linear[2].imag());
	}
	
	template<typename NumType>
	static void StokesToLinear(const NumType* stokes, std::complex<NumType> *linear)
	{
		linear[0] = stokes[0] + stokes[1];
		linear[1] = std::complex<NumType>(stokes[2], stokes[3]);
		linear[2] = std::complex<NumType>(stokes[2], -stokes[3]);
		linear[3] = stokes[0] - stokes[1];
	}
	
	template<typename NumType>
	static void CircularToStokes(const std::complex<NumType>* circular, NumType* stokes)
	{
		stokes[0] = (circular[0] + circular[3]).real()*0.5;
		stokes[1] = (circular[1] + circular[2]).real()*0.5;
		stokes[2] = (circular[1] - circular[2]).imag()*0.5;
		stokes[3] = (circular[0] - circular[3]).real()*0.5;
	}
};

typedef Polarization::PolarizationEnum PolarizationEnum;

#endif