1 /*****************************************************************************
5 ** Purpose: Routines for signal-procesing filters
6 ** Progammer: Kevin Rosenberg
7 ** Date Started: Aug 1984
9 ** This is part of the CTSim program
10 ** Copyright (C) 1983-2000 Kevin Rosenberg
12 ** $Id: procsignal.cpp,v 1.1 2000/08/19 23:00:05 kevin Exp $
14 ** This program is free software; you can redistribute it and/or modify
15 ** it under the terms of the GNU General Public License (version 2) as
16 ** published by the Free Software Foundation.
18 ** This program is distributed in the hope that it will be useful,
19 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
20 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 ** GNU General Public License for more details.
23 ** You should have received a copy of the GNU General Public License
24 ** along with this program; if not, write to the Free Software
25 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 ******************************************************************************/
30 // FilterMethod ID/Names
31 const int ProcessSignal::FILTER_METHOD_INVALID = -1;
32 const int ProcessSignal::FILTER_METHOD_CONVOLUTION = 0;
33 const int ProcessSignal::FILTER_METHOD_FOURIER = 1;
34 const int ProcessSignal::FILTER_METHOD_FOURIER_TABLE = 2;
35 const int ProcessSignal::FILTER_METHOD_FFT = 3;
37 const int ProcessSignal::FILTER_METHOD_FFTW = 4;
38 const int ProcessSignal::FILTER_METHOD_RFFTW =5 ;
40 const char* ProcessSignal::s_aszFilterMethodName[] = {
50 const char* ProcessSignal::s_aszFilterMethodTitle[] = {
53 {"Fouier Trigometric Table Lookout"},
57 {"Real/Half-Complex FFTW"},
60 const int ProcessSignal::s_iFilterMethodCount = sizeof(s_aszFilterMethodName) / sizeof(const char*);
62 // FilterGeneration ID/Names
63 const int ProcessSignal::FILTER_GENERATION_INVALID = -1;
64 const int ProcessSignal::FILTER_GENERATION_DIRECT = 0;
65 const int ProcessSignal::FILTER_GENERATION_INVERSE_FOURIER = 1;
66 const char* ProcessSignal::s_aszFilterGenerationName[] = {
70 const char* ProcessSignal::s_aszFilterGenerationTitle[] = {
74 const int ProcessSignal::s_iFilterGenerationCount = sizeof(s_aszFilterGenerationName) / sizeof(const char*);
77 // CLASS IDENTIFICATION
80 ProcessSignal::ProcessSignal (const char* szFilterName, const char* szFilterMethodName, double dBandwidth, double dSignalIncrement, int nSignalPoints, double dFilterParam, const char* szDomainName, const char* szFilterGenerationName, int iZeropad = 0, int iPreinterpolationFactor = 1)
81 : m_adFourierCosTable(NULL), m_adFourierSinTable(NULL), m_adFilter(NULL), m_fail(false)
83 m_idFilterMethod = convertFilterMethodNameToID (szFilterMethodName);
84 if (m_idFilterMethod == FILTER_METHOD_INVALID) {
86 m_failMessage = "Invalid filter method name ";
87 m_failMessage += szFilterMethodName;
90 m_idFilterGeneration = convertFilterGenerationNameToID (szFilterGenerationName);
91 if (m_idFilterGeneration == FILTER_GENERATION_INVALID) {
93 m_failMessage = "Invalid frequency filter name ";
94 m_failMessage += szFilterGenerationName;
97 m_idFilter = SignalFilter::convertFilterNameToID (szFilterName);
98 if (m_idFilter == SignalFilter::FILTER_INVALID) {
100 m_failMessage = "Invalid Filter name ";
101 m_failMessage += szFilterName;
104 m_idDomain = SignalFilter::convertDomainNameToID (szDomainName);
105 if (m_idDomain == SignalFilter::DOMAIN_INVALID) {
107 m_failMessage = "Invalid domain name ";
108 m_failMessage += szDomainName;
112 init (m_idFilter, m_idFilterMethod, dBandwidth, dSignalIncrement, nSignalPoints, dFilterParam, m_idDomain, m_idFilterGeneration, iZeropad, iPreinterpolationFactor);
117 ProcessSignal::init (const int idFilter, const int idFilterMethod, double dBandwidth, double dSignalIncrement, int nSignalPoints, double dFilterParam, const int idDomain, const int idFilterGeneration, const int iZeropad, const int iPreinterpolationFactor)
119 m_idFilter = idFilter;
120 m_idDomain = idDomain;
121 m_idFilterMethod = idFilterMethod;
122 m_idFilterGeneration = idFilterGeneration;
123 if (m_idFilter == SignalFilter::FILTER_INVALID || m_idDomain == SignalFilter::DOMAIN_INVALID || m_idFilterMethod == FILTER_METHOD_INVALID || m_idFilterGeneration == FILTER_GENERATION_INVALID) {
127 m_traceLevel = TRACE_NONE;
128 m_nameFilterMethod = convertFilterMethodIDToName (m_idFilterMethod);
129 m_nameFilterGeneration = convertFilterGenerationIDToName (m_idFilterGeneration);
130 m_dBandwidth = dBandwidth;
131 m_nSignalPoints = nSignalPoints;
132 m_dSignalInc = dSignalIncrement;
133 m_dFilterParam = dFilterParam;
134 m_iZeropad = iZeropad;
135 m_iPreinterpolationFactor = iPreinterpolationFactor;
137 if (m_idFilterMethod == FILTER_METHOD_FFT) {
139 m_idFilterMethod = FILTER_METHOD_RFFTW;
142 m_failMessage = "FFT not yet implemented";
147 bool m_bFrequencyFiltering = true;
148 if (m_idFilterMethod == FILTER_METHOD_CONVOLUTION)
149 m_bFrequencyFiltering = false;
151 // Spatial-based filtering
152 if (! m_bFrequencyFiltering) {
154 if (m_idFilterGeneration == FILTER_GENERATION_DIRECT) {
155 m_nFilterPoints = 2 * m_nSignalPoints - 1;
156 m_dFilterMin = -m_dSignalInc * (m_nSignalPoints - 1);
157 m_dFilterMax = m_dSignalInc * (m_nSignalPoints - 1);
158 m_dFilterInc = (m_dFilterMax - m_dFilterMin) / (m_nFilterPoints - 1);
159 SignalFilter filter (m_idFilter, m_dFilterMin, m_dFilterMax, m_nFilterPoints, m_dBandwidth, m_dFilterParam, SignalFilter::DOMAIN_SPATIAL);
160 m_adFilter = new double[ m_nFilterPoints ];
161 filter.copyFilterData (m_adFilter, 0, m_nFilterPoints);
162 } else if (m_idFilterGeneration == FILTER_GENERATION_INVERSE_FOURIER) {
163 m_nFilterPoints = m_nSignalPoints;
164 m_dFilterMin = -1. / (2 * m_dSignalInc);
165 m_dFilterMax = 1. / (2 * m_dSignalInc);
166 m_dFilterInc = (m_dFilterMax - m_dFilterMin) / (m_nFilterPoints - 1);
167 SignalFilter filter (m_idFilter, m_dFilterMin, m_dFilterMax, m_nFilterPoints, m_dBandwidth, m_dFilterParam, SignalFilter::DOMAIN_FREQUENCY);
168 m_adFilter = new double[ m_nFilterPoints ];
169 double adFrequencyFilter [m_nFilterPoints];
170 double adInverseFilter [m_nFilterPoints];
171 filter.copyFilterData (adFrequencyFilter, 0, m_nFilterPoints);
172 shuffleNaturalToFourierOrder (adFrequencyFilter, m_nFilterPoints);
173 ProcessSignal::finiteFourierTransform (adFrequencyFilter, adInverseFilter, m_nFilterPoints, 1);
174 for (int i = 0; i < m_nFilterPoints; i++)
175 m_adFilter [i] = adInverseFilter[i];
179 // Frequency-based filtering
180 else if (m_bFrequencyFiltering) {
182 // calculate number of filter points with zeropadding
183 m_nFilterPoints = m_nSignalPoints;
184 if (m_iZeropad > 0) {
185 double logBase2 = log(m_nSignalPoints) / log(2);
186 int nextPowerOf2 = static_cast<int>(floor(logBase2));
187 if (logBase2 != floor(logBase2))
189 nextPowerOf2 += (m_iZeropad - 1);
190 m_nFilterPoints = 1 << nextPowerOf2;
191 if (m_traceLevel >= TRACE_TEXT)
192 cout << "nFilterPoints = " << m_nFilterPoints << endl;
194 m_nOutputPoints = m_nFilterPoints * m_iPreinterpolationFactor;
196 if (m_idFilterGeneration == FILTER_GENERATION_DIRECT) {
197 m_dFilterMin = -1. / (2 * m_dSignalInc);
198 m_dFilterMax = 1. / (2 * m_dSignalInc);
199 m_dFilterInc = (m_dFilterMax - m_dFilterMin) / (m_nFilterPoints - 1);
200 SignalFilter filter (m_idFilter, m_dFilterMin, m_dFilterMax, m_nFilterPoints, m_dBandwidth, m_dFilterParam, SignalFilter::DOMAIN_FREQUENCY);
201 m_adFilter = new double [m_nFilterPoints];
202 filter.copyFilterData (m_adFilter, 0, m_nFilterPoints);
203 shuffleNaturalToFourierOrder (m_adFilter, m_nFilterPoints);
204 } else if (m_idFilterGeneration == FILTER_GENERATION_INVERSE_FOURIER) {
205 m_nFilterPoints = 2 * m_nSignalPoints - 1;
206 m_dFilterMin = -m_dSignalInc * (m_nSignalPoints - 1);
207 m_dFilterMax = m_dSignalInc * (m_nSignalPoints - 1);
208 m_dFilterInc = (m_dFilterMax - m_dFilterMin) / (m_nFilterPoints - 1);
209 double adSpatialFilter [m_nFilterPoints];
210 double adInverseFilter [m_nFilterPoints];
211 SignalFilter filter (m_idFilter, m_dFilterMin, m_dFilterMax, m_nFilterPoints, m_dBandwidth, m_dFilterParam, SignalFilter::DOMAIN_SPATIAL);
212 filter.copyFilterData (adSpatialFilter, 0, m_nFilterPoints);
213 m_adFilter = new double [m_nFilterPoints];
214 finiteFourierTransform (adSpatialFilter, adInverseFilter, m_nFilterPoints, -1);
215 for (int i = 0; i < m_nFilterPoints; i++)
216 m_adFilter [i] = adInverseFilter[i];
220 // precalculate sin and cosine tables for fourier transform
221 if (m_idFilterMethod == FILTER_METHOD_FOURIER_TABLE) {
222 int nFourier = max(m_nFilterPoints,m_nOutputPoints) * max(m_nFilterPoints, m_nOutputPoints) + 1;
223 double angleIncrement = (2. * PI) / m_nFilterPoints;
224 m_adFourierCosTable = new double[ nFourier ];
225 m_adFourierSinTable = new double[ nFourier ];
227 for (int i = 0; i < nFourier; i++) {
228 m_adFourierCosTable[i] = cos (angle);
229 m_adFourierSinTable[i] = sin (angle);
230 angle += angleIncrement;
235 if (m_idFilterMethod == FILTER_METHOD_FFTW || m_idFilterMethod == FILTER_METHOD_RFFTW) {
236 for (int i = 0; i < m_nFilterPoints; i++) //fftw uses unnormalized fft
237 m_adFilter[i] /= m_nFilterPoints;
240 if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
241 m_realPlanForward = rfftw_create_plan (m_nFilterPoints, FFTW_REAL_TO_COMPLEX, FFTW_ESTIMATE);
242 m_realPlanBackward = rfftw_create_plan (m_nOutputPoints, FFTW_COMPLEX_TO_REAL, FFTW_ESTIMATE);
243 m_adRealFftInput = new fftw_real [ m_nFilterPoints ];
244 m_adRealFftSignal = new fftw_real [ m_nOutputPoints ];
245 for (int i = 0; i < m_nFilterPoints; i++)
246 m_adRealFftInput[i] = 0;
247 } else if (m_idFilterMethod == FILTER_METHOD_FFTW) {
248 m_complexPlanForward = fftw_create_plan (m_nFilterPoints, FFTW_FORWARD, FFTW_ESTIMATE);
249 m_complexPlanBackward = fftw_create_plan (m_nOutputPoints, FFTW_BACKWARD, FFTW_ESTIMATE);
250 m_adComplexFftInput = new fftw_complex [ m_nFilterPoints ];
251 m_adComplexFftSignal = new fftw_complex [ m_nOutputPoints ];
252 for (int i = 0; i < m_nFilterPoints; i++)
253 m_adComplexFftInput[i].re = m_adComplexFftInput[i].im = 0;
254 for (int i = 0; i < m_nOutputPoints; i++)
255 m_adComplexFftSignal[i].re = m_adComplexFftSignal[i].im = 0;
261 ProcessSignal::~ProcessSignal (void)
263 delete [] m_adFourierSinTable;
264 delete [] m_adFourierCosTable;
267 if (m_idFilterMethod == FILTER_METHOD_FFTW) {
268 fftw_destroy_plan(m_complexPlanForward);
269 fftw_destroy_plan(m_complexPlanBackward);
270 delete [] m_adComplexFftInput;
271 delete [] m_adComplexFftSignal;
273 if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
274 rfftw_destroy_plan(m_realPlanForward);
275 rfftw_destroy_plan(m_realPlanBackward);
276 delete [] m_adRealFftInput;
277 delete [] m_adRealFftSignal;
283 ProcessSignal::convertFilterMethodNameToID (const char* const filterMethodName)
285 int fmID = FILTER_METHOD_INVALID;
287 for (int i = 0; i < s_iFilterMethodCount; i++)
288 if (strcasecmp (filterMethodName, s_aszFilterMethodName[i]) == 0) {
297 ProcessSignal::convertFilterMethodIDToName (const int fmID)
299 static const char *name = "";
301 if (fmID >= 0 && fmID < s_iFilterMethodCount)
302 return (s_aszFilterMethodName [fmID]);
308 ProcessSignal::convertFilterMethodIDToTitle (const int fmID)
310 static const char *title = "";
312 if (fmID >= 0 && fmID < s_iFilterMethodCount)
313 return (s_aszFilterMethodTitle [fmID]);
320 ProcessSignal::convertFilterGenerationNameToID (const char* const fgName)
322 int fgID = FILTER_GENERATION_INVALID;
324 for (int i = 0; i < s_iFilterGenerationCount; i++)
325 if (strcasecmp (fgName, s_aszFilterGenerationName[i]) == 0) {
334 ProcessSignal::convertFilterGenerationIDToName (const int fgID)
336 static const char *name = "";
338 if (fgID >= 0 && fgID < s_iFilterGenerationCount)
339 return (s_aszFilterGenerationName [fgID]);
345 ProcessSignal::convertFilterGenerationIDToTitle (const int fgID)
347 static const char *name = "";
349 if (fgID >= 0 && fgID < s_iFilterGenerationCount)
350 return (s_aszFilterGenerationTitle [fgID]);
356 ProcessSignal::filterSignal (const float input[], double output[]) const
358 if (m_idFilterMethod == FILTER_METHOD_CONVOLUTION) {
359 for (int i = 0; i < m_nSignalPoints; i++)
360 output[i] = convolve (input, m_dSignalInc, i, m_nSignalPoints);
361 } else if (m_idFilterMethod == FILTER_METHOD_FOURIER) {
362 double inputSignal[m_nFilterPoints];
363 for (int i = 0; i < m_nSignalPoints; i++)
364 inputSignal[i] = input[i];
365 for (int i = m_nSignalPoints; i < m_nFilterPoints; i++)
366 inputSignal[i] = 0; // zeropad
367 complex<double> fftSignal[m_nFilterPoints];
368 finiteFourierTransform (inputSignal, fftSignal, m_nFilterPoints, -1);
369 for (int i = 0; i < m_nFilterPoints; i++)
370 fftSignal[i] *= m_adFilter[i];
371 double inverseFourier[m_nFilterPoints];
372 finiteFourierTransform (fftSignal, inverseFourier, m_nFilterPoints, 1);
373 for (int i = 0; i < m_nSignalPoints; i++)
374 output[i] = inverseFourier[i];
375 } else if (m_idFilterMethod == FILTER_METHOD_FOURIER_TABLE) {
376 double inputSignal[m_nFilterPoints];
377 for (int i = 0; i < m_nSignalPoints; i++)
378 inputSignal[i] = input[i];
379 for (int i = m_nSignalPoints; i < m_nFilterPoints; i++)
380 inputSignal[i] = 0; // zeropad
381 complex<double> fftSignal[m_nFilterPoints];
382 finiteFourierTransform (inputSignal, fftSignal, -1);
383 for (int i = 0; i < m_nFilterPoints; i++)
384 fftSignal[i] *= m_adFilter[i];
385 double inverseFourier[m_nFilterPoints];
386 finiteFourierTransform (fftSignal, inverseFourier, 1);
387 for (int i = 0; i < m_nSignalPoints; i++)
388 output[i] = inverseFourier[i];
391 else if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
392 for (int i = 0; i < m_nSignalPoints; i++)
393 m_adRealFftInput[i] = input[i];
395 fftw_real fftOutput [ m_nFilterPoints ];
396 rfftw_one (m_realPlanForward, m_adRealFftInput, fftOutput);
397 for (int i = 0; i < m_nFilterPoints; i++)
398 m_adRealFftSignal[i] = m_adFilter[i] * fftOutput[i];
399 for (int i = m_nFilterPoints; i < m_nOutputPoints; i++)
400 m_adRealFftSignal[i] = 0;
402 fftw_real ifftOutput [ m_nOutputPoints ];
403 rfftw_one (m_realPlanBackward, m_adRealFftSignal, ifftOutput);
404 for (int i = 0; i < m_nSignalPoints * m_iPreinterpolationFactor; i++)
405 output[i] = ifftOutput[i];
406 } else if (m_idFilterMethod == FILTER_METHOD_FFTW) {
407 for (int i = 0; i < m_nSignalPoints; i++)
408 m_adComplexFftInput[i].re = input[i];
410 fftw_complex fftOutput [ m_nFilterPoints ];
411 fftw_one (m_complexPlanForward, m_adComplexFftInput, fftOutput);
412 for (int i = 0; i < m_nFilterPoints; i++) {
413 m_adComplexFftSignal[i].re = m_adFilter[i] * fftOutput[i].re;
414 m_adComplexFftSignal[i].im = m_adFilter[i] * fftOutput[i].im;
416 fftw_complex ifftOutput [ m_nOutputPoints ];
417 fftw_one (m_complexPlanBackward, m_adComplexFftSignal, ifftOutput);
418 for (int i = 0; i < m_nSignalPoints * m_iPreinterpolationFactor; i++)
419 output[i] = ifftOutput[i].re;
426 * convolve Discrete convolution of two functions
429 * r = convolve (f1, f2, dx, n, np, func_type)
430 * double r Convolved result
431 * double f1[], f2[] Functions to be convolved
432 * double dx Difference between successive x values
433 * int n Array index to center convolution about
434 * int np Number of points in f1 array
435 * int func_type EVEN or ODD or EVEN_AND_ODD function f2
438 * f1 is the projection data, its indices range from 0 to np - 1.
439 * The index for f2, the filter, ranges from -(np-1) to (np-1).
440 * There are 3 ways to handle the negative vertices of f2:
441 * 1. If we know f2 is an EVEN function, then f2[-n] = f2[n].
442 * All filters used in reconstruction are even.
443 * 2. If we know f2 is an ODD function, then f2[-n] = -f2[n]
444 * 3. If f2 is both ODD AND EVEN, then we must store the value of f2
445 * for negative indices. Since f2 must range from -(np-1) to (np-1),
446 * if we add (np - 1) to f2's array index, then f2's index will
447 * range from 0 to 2 * (np - 1), and the origin, x = 0, will be
448 * stored at f2[np-1].
452 ProcessSignal::convolve (const double func[], const double dx, const int n, const int np) const
456 #if UNOPTIMIZED_CONVOLUTION
457 for (int i = 0; i < np; i++)
458 sum += func[i] * m_adFilter[n - i + (np - 1)];
460 double* f2 = m_adFilter + n + (np - 1);
461 for (int i = 0; i < np; i++)
462 sum += *func++ * *f2--;
470 ProcessSignal::convolve (const float func[], const double dx, const int n, const int np) const
474 #if UNOPTIMIZED_CONVOLUTION
475 for (int i = 0; i < np; i++)
476 sum += func[i] * m_adFilter[n - i + (np - 1)];
478 double* f2 = m_adFilter + n + (np - 1);
479 for (int i = 0; i < np; i++)
480 sum += *func++ * *f2--;
488 ProcessSignal::finiteFourierTransform (const double input[], double output[], const int n, int direction)
490 complex<double> complexOutput[n];
492 finiteFourierTransform (input, complexOutput, n, direction);
493 for (int i = 0; i < n; i++)
494 output[i] = abs(complexOutput[n]);
498 ProcessSignal::finiteFourierTransform (const double input[], complex<double> output[], const int n, int direction)
505 double angleIncrement = direction * 2 * PI / n;
506 for (int i = 0; i < n; i++) {
509 for (int j = 0; j < n; j++) {
510 double angle = i * j * angleIncrement;
511 sumReal += input[j] * cos(angle);
512 sumImag += input[j] * sin(angle);
518 output[i] = complex<double> (sumReal, sumImag);
524 ProcessSignal::finiteFourierTransform (const complex<double> input[], complex<double> output[], const int n, int direction)
531 double angleIncrement = direction * 2 * PI / n;
532 for (int i = 0; i < n; i++) {
533 complex<double> sum (0,0);
534 for (int j = 0; j < n; j++) {
535 double angle = i * j * angleIncrement;
536 complex<double> exponentTerm (cos(angle), sin(angle));
537 sum += input[j] * exponentTerm;
547 ProcessSignal::finiteFourierTransform (const complex<double> input[], double output[], const int n, int direction)
554 double angleIncrement = direction * 2 * PI / n;
555 for (int i = 0; i < n; i++) {
557 for (int j = 0; j < n; j++) {
558 double angle = i * j * angleIncrement;
559 sumReal += input[j].real() * cos(angle) - input[j].imag() * sin(angle);
568 // Table-based routines
571 ProcessSignal::finiteFourierTransform (const double input[], complex<double> output[], int direction) const
578 for (int i = 0; i < m_nFilterPoints; i++) {
579 double sumReal = 0, sumImag = 0;
580 for (int j = 0; j < m_nFilterPoints; j++) {
581 int tableIndex = i * j;
583 sumReal += input[j] * m_adFourierCosTable[tableIndex];
584 sumImag += input[j] * m_adFourierSinTable[tableIndex];
586 sumReal += input[j] * m_adFourierCosTable[tableIndex];
587 sumImag -= input[j] * m_adFourierSinTable[tableIndex];
591 sumReal /= m_nFilterPoints;
592 sumImag /= m_nFilterPoints;
594 output[i] = complex<double> (sumReal, sumImag);
598 // (a+bi) * (c + di) = (ac - bd) + (ad + bc)i
600 ProcessSignal::finiteFourierTransform (const complex<double> input[], complex<double> output[], int direction) const
607 for (int i = 0; i < m_nFilterPoints; i++) {
608 double sumReal = 0, sumImag = 0;
609 for (int j = 0; j < m_nFilterPoints; j++) {
610 int tableIndex = i * j;
612 sumReal += input[j].real() * m_adFourierCosTable[tableIndex]
613 - input[j].imag() * m_adFourierSinTable[tableIndex];
614 sumImag += input[j].real() * m_adFourierSinTable[tableIndex]
615 + input[j].imag() * m_adFourierCosTable[tableIndex];
617 sumReal += input[j].real() * m_adFourierCosTable[tableIndex]
618 - input[j].imag() * -m_adFourierSinTable[tableIndex];
619 sumImag += input[j].real() * -m_adFourierSinTable[tableIndex]
620 + input[j].imag() * m_adFourierCosTable[tableIndex];
624 sumReal /= m_nFilterPoints;
625 sumImag /= m_nFilterPoints;
627 output[i] = complex<double> (sumReal, sumImag);
632 ProcessSignal::finiteFourierTransform (const complex<double> input[], double output[], int direction) const
639 for (int i = 0; i < m_nFilterPoints; i++) {
641 for (int j = 0; j < m_nFilterPoints; j++) {
642 int tableIndex = i * j;
644 sumReal += input[j].real() * m_adFourierCosTable[tableIndex]
645 - input[j].imag() * m_adFourierSinTable[tableIndex];
647 sumReal += input[j].real() * m_adFourierCosTable[tableIndex]
648 - input[j].imag() * -m_adFourierSinTable[tableIndex];
652 sumReal /= m_nFilterPoints;
658 // Odd Number of Points
659 // Natural Frequency Order: -(n-1)/2...-1,0,1...(n-1)/2
660 // Fourier Frequency Order: 0, 1..(n-1)/2,-(n-1)/2...-1
661 // Even Number of Points
662 // Natural Frequency Order: -n/2...-1,0,1...((n/2)-1)
663 // Fourier Frequency Order: 0,1...((n/2)-1),-n/2...-1
666 ProcessSignal::shuffleNaturalToFourierOrder (double* pdVector, const int n)
668 double* pdTemp = new double [n];
670 int iHalfN = (n - 1) / 2;
672 pdTemp[0] = pdVector[iHalfN];
673 for (int i = 1; i <= iHalfN; i++)
674 pdTemp[i] = pdVector[i+iHalfN];
675 for (int i = iHalfN+1; i < n; i++)
676 pdTemp[i] = pdVector[i-iHalfN];
679 pdTemp[0] = pdVector[iHalfN];
682 for (int i = 0; i < n; i++)
683 pdVector[i] = pdTemp[i];
689 ProcessSignal::shuffleFourierToNaturalOrder (double* pdVector, const int n)
691 double* pdTemp = new double [n];
693 int iHalfN = (n - 1) / 2;
695 pdTemp[iHalfN] = pdVector[0];
696 for (int i = 1; i <= iHalfN; i++)
697 pdTemp[i] = pdVector[i+iHalfN];
698 for (int i = iHalfN+1; i < n; i++)
699 pdTemp[i] = pdVector[i-iHalfN];
702 pdTemp[iHalfN] = pdVector[0];
705 for (int i = 0; i < n; i++)
706 pdVector[i] = pdTemp[i];