/*****************************************************************************
-** FILE IDENTIFICATION
+** File IDENTIFICATION
**
** Name: filter.cpp
** Purpose: Routines for signal-procesing filters
** This is part of the CTSim program
** Copyright (C) 1983-2000 Kevin Rosenberg
**
-** $Id: filter.cpp,v 1.4 2000/06/25 17:32:24 kevin Exp $
+** $Id: filter.cpp,v 1.18 2000/07/15 08:36:13 kevin Exp $
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License (version 2) as
#include "ct.h"
+int SignalFilter::N_INTEGRAL=500; //static member
+
/* NAME
* SignalFilter::SignalFilter Construct a signal
*
* SYNOPSIS
- * f = SignalFilter (filt_type, bw, xmin, xmax, n, param, domain, analytic)
+ * f = SignalFilter (filt_type, bw, filterMin, filterMax, n, param, domain, analytic)
* double f Generated filter vector
* int filt_type Type of filter wanted
* double bw Bandwidth of filter
- * double xmin, xmax Filter limits
- * int n Number of points in filter
+ * double filterMin, filterMax Filter limits
+ * int nSignalPoints Number of points in signal
* double param General input parameter to filters
- * int domain FREQ or SPATIAL domain wanted
- * int numint Number if intervals for calculating discrete inverse fourier xform
- * for spatial domain filters. For ANALYTIC solutions, use numint = 0
+ * int domain FREQUENCY or SPATIAL domain wanted
*/
-SignalFilter::SignalFilter (const char* filterName, double bw, double xmin, double xmax, int n, double param, const char* domainName, int numIntegral = 0)
+SignalFilter::SignalFilter (const char* filterName, const char* filterMethodName, double bw, double signalIncrement, int nSignalPoints, double param, const char* domainName, int zeropad = 0, int preinterpolationFactor = 1)
{
m_vecFilter = NULL;
+ m_vecFourierCosTable = NULL;
+ m_vecFourierSinTable = NULL;
m_idFilter = convertFilterNameToID (filterName);
if (m_idFilter == FILTER_INVALID) {
m_fail = true;
m_failMessage += filterName;
return;
}
+ m_idFilterMethod = convertFilterMethodNameToID (filterMethodName);
+ if (m_idFilterMethod == FILTER_METHOD_INVALID) {
+ m_fail = true;
+ m_failMessage = "Invalid filter method name ";
+ m_failMessage += filterMethodName;
+ return;
+ }
m_idDomain = convertDomainNameToID (domainName);
if (m_idDomain == DOMAIN_INVALID) {
m_fail = true;
m_failMessage += domainName;
return;
}
- init (m_idFilter, bw, xmin, xmax, n, param, m_idDomain, numIntegral);
+ init (m_idFilter, m_idFilterMethod, bw, signalIncrement, nSignalPoints, param, m_idDomain, zeropad, preinterpolationFactor);
}
-SignalFilter::SignalFilter (const FilterID filterID, double bw, double xmin, double xmax, int n, double param, const DomainID domainID, int numIntegral = 0)
+SignalFilter::SignalFilter (const FilterID filterID, const FilterMethodID filterMethodID, double bw, double signalIncrement, int nSignalPoints, double param, const DomainID domainID, int zeropad = 0, int preinterpolationFactor = 1)
{
- init (filterID, bw, xmin, xmax, n, param, domainID, numIntegral);
+ init (filterID, filterMethodID, bw, signalIncrement, nSignalPoints, param, domainID, zeropad, preinterpolationFactor);
}
-SignalFilter::SignalFilter (const char* filterName, const char* domainName, double bw, double param, int numIntegral = 0)
+SignalFilter::SignalFilter (const char* filterName, const char* domainName, double bw, double param)
{
m_bw = bw;
- m_nPoints = 0;
+ m_nSignalPoints = 0;
+ m_nFilterPoints = 0;
m_vecFilter = NULL;
+ m_vecFourierCosTable = NULL;
+ m_vecFourierSinTable = NULL;
m_filterParam = param;
- m_numIntegral = numIntegral;
m_idFilter = convertFilterNameToID (filterName);
if (m_idFilter == FILTER_INVALID) {
m_fail = true;
}
void
-SignalFilter::init (const FilterID filterID, double bw, double xmin, double xmax, int n, double param, const DomainID domainID, int numint)
+SignalFilter::init (const FilterID filterID, const FilterMethodID filterMethodID, double bw, double signalIncrement, int nSignalPoints, double filterParam, const DomainID domainID, int zeropad, int preinterpolationFactor)
{
m_bw = bw;
m_idFilter = filterID;
m_idDomain = domainID;
- if (m_idFilter == FILTER_INVALID || m_idDomain == DOMAIN_INVALID) {
+ m_idFilterMethod = filterMethodID;
+ if (m_idFilter == FILTER_INVALID || m_idDomain == DOMAIN_INVALID || m_idFilterMethod == FILTER_METHOD_INVALID) {
m_fail = true;
return;
}
+ m_traceLevel = TRACE_NONE;
m_nameFilter = convertFilterIDToName (m_idFilter);
m_nameDomain = convertDomainIDToName (m_idDomain);
+ m_nameFilterMethod = convertFilterMethodIDToName (m_idFilterMethod);
m_fail = false;
- m_nPoints = n;
- m_xmin = xmin;
- m_xmax = xmax;
- m_numIntegral = numint;
- m_filterParam = param;
- m_vecFilter = new double[n];
-
- double xinc = (m_xmax - m_xmin) / (m_nPoints - 1);
-
- if (m_idFilter == FILTER_SHEPP) {
- double a = 2 * m_bw;
- double c = - 4. / (a * a);
- int center = (m_nPoints - 1) / 2;
- int sidelen = center;
- m_vecFilter[center] = 4. / (a * a);
-
- for (int i = 1; i <= sidelen; i++ )
- m_vecFilter [center + i] = m_vecFilter [center - i] = c / (4 * (i * i) - 1);
- } else if (m_idDomain == DOMAIN_FREQ) {
- double x;
- int i;
- for (x = m_xmin, i = 0; i < m_nPoints; x += xinc, i++)
- m_vecFilter[i] = frequencyResponse (x, param);
- } else if (m_idDomain == DOMAIN_SPATIAL) {
- double x;
- int i;
- for (x = m_xmin, i = 0; i < m_nPoints; x += xinc, i++)
- if (numint == 0)
- m_vecFilter[i] = spatialResponseAnalytic (x, param);
- else
- m_vecFilter[i] = spatialResponseCalc (x, param, numint);
- } else {
+ m_nSignalPoints = nSignalPoints;
+ m_signalInc = signalIncrement;
+ m_filterParam = filterParam;
+ m_zeropad = zeropad;
+ m_preinterpolationFactor = preinterpolationFactor;
+
+ m_vecFourierCosTable = NULL;
+ m_vecFourierSinTable = NULL;
+ m_vecFilter = NULL;
+
+ if (m_idFilterMethod == FILTER_METHOD_FFT) {
+#if HAVE_FFTW
+ m_idFilterMethod = FILTER_METHOD_RFFTW;
+#else
+ m_fail = true;
+ m_failMessage = "FFT not yet implemented";
+ return;
+#endif
+ }
+
+ if (m_idFilterMethod == FILTER_METHOD_FOURIER || m_idFilterMethod == FILTER_METHOD_FOURIER_TABLE || m_idFilterMethod == FILTER_METHOD_FFT
+#if HAVE_FFTW
+ || m_idFilterMethod == FILTER_METHOD_FFTW || m_idFilterMethod == FILTER_METHOD_RFFTW
+#endif
+ ) {
+ m_nFilterPoints = m_nSignalPoints;
+ if (m_zeropad > 0) {
+ double logBase2 = log(m_nSignalPoints) / log(2);
+ int nextPowerOf2 = static_cast<int>(floor(logBase2));
+ if (logBase2 != floor(logBase2))
+ nextPowerOf2++;
+ nextPowerOf2 += (m_zeropad - 1);
+ m_nFilterPoints = 1 << nextPowerOf2;
+ if (m_traceLevel >= TRACE_TEXT)
+ cout << "nFilterPoints = " << m_nFilterPoints << endl;
+ }
+ m_nOutputPoints = m_nFilterPoints * m_preinterpolationFactor;
+ m_filterMin = -1. / (2 * m_signalInc);
+ m_filterMax = 1. / (2 * m_signalInc);
+ m_filterInc = (m_filterMax - m_filterMin) / m_nFilterPoints;
+ m_vecFilter = new double [m_nFilterPoints];
+ int halfFilter = m_nFilterPoints / 2;
+ for (int i = 0; i <= halfFilter; i++)
+ m_vecFilter[i] = static_cast<double>(i) / halfFilter/ (2. * m_signalInc);
+ for (int i = 1; i <= halfFilter; i++)
+ m_vecFilter[m_nFilterPoints - i] = static_cast<double>(i) / halfFilter / (2. * m_signalInc);
+ }
+
+ // precalculate sin and cosine tables for fourier transform
+ if (m_idFilterMethod == FILTER_METHOD_FOURIER_TABLE) {
+ int nFourier = max(m_nFilterPoints,m_nOutputPoints) * max(m_nFilterPoints, m_nOutputPoints) + 1;
+ double angleIncrement = (2. * PI) / m_nFilterPoints;
+ m_vecFourierCosTable = new double[ nFourier ];
+ m_vecFourierSinTable = new double[ nFourier ];
+ double angle = 0;
+ for (int i = 0; i < nFourier; i++) {
+ m_vecFourierCosTable[i] = cos (angle);
+ m_vecFourierSinTable[i] = sin (angle);
+ angle += angleIncrement;
+ }
+ }
+
+#if HAVE_FFTW
+ if (m_idFilterMethod == FILTER_METHOD_FFTW || m_idFilterMethod == FILTER_METHOD_RFFTW) {
+ for (int i = 0; i < m_nFilterPoints; i++) //fftw uses unnormalized fft
+ m_vecFilter[i] /= m_nFilterPoints;
+ }
+
+ if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
+ m_realPlanForward = rfftw_create_plan (m_nFilterPoints, FFTW_REAL_TO_COMPLEX, FFTW_ESTIMATE);
+ m_realPlanBackward = rfftw_create_plan (m_nOutputPoints, FFTW_COMPLEX_TO_REAL, FFTW_ESTIMATE);
+ m_vecRealFftInput = new fftw_real [ m_nFilterPoints ];
+ m_vecRealFftSignal = new fftw_real [ m_nOutputPoints ];
+ for (int i = 0; i < m_nFilterPoints; i++)
+ m_vecRealFftInput[i] = 0;
+ } else if (m_idFilterMethod == FILTER_METHOD_FFTW) {
+ m_complexPlanForward = fftw_create_plan (m_nFilterPoints, FFTW_FORWARD, FFTW_ESTIMATE);
+ m_complexPlanBackward = fftw_create_plan (m_nOutputPoints, FFTW_BACKWARD, FFTW_ESTIMATE);
+ m_vecComplexFftInput = new fftw_complex [ m_nFilterPoints ];
+ m_vecComplexFftSignal = new fftw_complex [ m_nOutputPoints ];
+ for (int i = 0; i < m_nFilterPoints; i++)
+ m_vecComplexFftInput[i].re = m_vecComplexFftInput[i].im = 0;
+ for (int i = 0; i < m_nOutputPoints; i++)
+ m_vecComplexFftSignal[i].re = m_vecComplexFftSignal[i].im = 0;
+ }
+#endif
+
+ if (m_idFilterMethod == FILTER_METHOD_CONVOLUTION) {
+ m_nFilterPoints = 2 * m_nSignalPoints - 1;
+ m_filterMin = -m_signalInc * (m_nSignalPoints - 1);
+ m_filterMax = m_signalInc * (m_nSignalPoints - 1);
+ m_filterInc = (m_filterMax - m_filterMin) / (m_nFilterPoints - 1);
+ m_vecFilter = new double[ m_nFilterPoints ];
+
+ if (m_idFilter == FILTER_SHEPP) {
+ double a = 2 * m_bw;
+ double c = - 4. / (a * a);
+ int center = (m_nFilterPoints - 1) / 2;
+ int sidelen = center;
+ m_vecFilter[center] = 4. / (a * a);
+
+ for (int i = 1; i <= sidelen; i++ )
+ m_vecFilter [center + i] = m_vecFilter [center - i] = c / (4 * (i * i) - 1);
+ } else if (m_idDomain == DOMAIN_FREQUENCY) {
+ double x;
+ int i;
+ for (x = m_filterMin, i = 0; i < m_nFilterPoints; x += m_filterInc, i++)
+ m_vecFilter[i] = frequencyResponse (x, m_filterParam);
+ } else if (m_idDomain == DOMAIN_SPATIAL) {
+ double x;
+ int i;
+ for (x = m_filterMin, i = 0; i < m_nFilterPoints; x += m_filterInc, i++)
+ if (haveAnalyticSpatial(m_idFilter))
+ m_vecFilter[i] = spatialResponseAnalytic (x, m_filterParam);
+ else
+ m_vecFilter[i] = spatialResponseCalc (x, m_filterParam);
+ } else {
m_failMessage = "Illegal domain name ";
m_failMessage += m_idDomain;
m_fail = true;
+ }
}
}
SignalFilter::~SignalFilter (void)
{
- delete m_vecFilter;
+ delete [] m_vecFilter;
+ delete [] m_vecFourierSinTable;
+ delete [] m_vecFourierCosTable;
+
+#if HAVE_FFTW
+ if (m_idFilterMethod == FILTER_METHOD_FFTW) {
+ fftw_destroy_plan(m_complexPlanForward);
+ fftw_destroy_plan(m_complexPlanBackward);
+ delete [] m_vecComplexFftInput;
+ delete [] m_vecComplexFftSignal;
+ }
+ if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
+ rfftw_destroy_plan(m_realPlanForward);
+ rfftw_destroy_plan(m_realPlanBackward);
+ delete [] m_vecRealFftInput;
+ delete [] m_vecRealFftSignal;
+ }
+#endif
}
-SignalFilter::FilterID
+const SignalFilter::FilterID
SignalFilter::convertFilterNameToID (const char *filterName)
{
FilterID filterID = FILTER_INVALID;
return (name);
}
+const SignalFilter::FilterMethodID
+SignalFilter::convertFilterMethodNameToID (const char* const filterMethodName)
+{
+ FilterMethodID fmID = FILTER_METHOD_INVALID;
+
+ if (strcasecmp (filterMethodName, FILTER_METHOD_CONVOLUTION_STR) == 0)
+ fmID = FILTER_METHOD_CONVOLUTION;
+ else if (strcasecmp (filterMethodName, FILTER_METHOD_FOURIER_STR) == 0)
+ fmID = FILTER_METHOD_FOURIER;
+ else if (strcasecmp (filterMethodName, FILTER_METHOD_FOURIER_TABLE_STR) == 0)
+ fmID = FILTER_METHOD_FOURIER_TABLE;
+ else if (strcasecmp (filterMethodName, FILTER_METHOD_FFT_STR) == 0)
+ fmID = FILTER_METHOD_FFT;
+#if HAVE_FFTW
+ else if (strcasecmp (filterMethodName, FILTER_METHOD_FFTW_STR) == 0)
+ fmID = FILTER_METHOD_FFTW;
+ else if (strcasecmp (filterMethodName, FILTER_METHOD_RFFTW_STR) == 0)
+ fmID = FILTER_METHOD_RFFTW;
+#endif
+
+ return (fmID);
+}
+
+const char *
+SignalFilter::convertFilterMethodIDToName (const FilterMethodID fmID)
+{
+ const char *name = "";
+
+ if (fmID == FILTER_METHOD_CONVOLUTION)
+ return (FILTER_METHOD_CONVOLUTION_STR);
+ else if (fmID == FILTER_METHOD_FOURIER)
+ return (FILTER_METHOD_FOURIER_STR);
+ else if (fmID == FILTER_METHOD_FOURIER_TABLE)
+ return (FILTER_METHOD_FOURIER_TABLE_STR);
+ else if (fmID == FILTER_METHOD_FFT)
+ return (FILTER_METHOD_FFT_STR);
+#if HAVE_FFTW
+ else if (fmID == FILTER_METHOD_FFTW)
+ return (FILTER_METHOD_FFTW_STR);
+ else if (fmID == FILTER_METHOD_RFFTW)
+ return (FILTER_METHOD_RFFTW_STR);
+#endif
+
+ return (name);
+}
+
const SignalFilter::DomainID
SignalFilter::convertDomainNameToID (const char* const domainName)
{
if (strcasecmp (domainName, DOMAIN_SPATIAL_STR) == 0)
dID = DOMAIN_SPATIAL;
- else if (strcasecmp (domainName, DOMAIN_FREQ_STR) == 0)
- dID = DOMAIN_FREQ;
+ else if (strcasecmp (domainName, DOMAIN_FREQUENCY_STR) == 0)
+ dID = DOMAIN_FREQUENCY;
return (dID);
}
if (domain == DOMAIN_SPATIAL)
return (DOMAIN_SPATIAL_STR);
- else if (domain == DOMAIN_FREQ)
- return (DOMAIN_FREQ_STR);
+ else if (domain == DOMAIN_FREQUENCY)
+ return (DOMAIN_FREQUENCY_STR);
return (name);
}
+void
+SignalFilter::filterSignal (const float input[], double output[]) const
+{
+ if (m_idFilterMethod == FILTER_METHOD_CONVOLUTION) {
+ for (int i = 0; i < m_nSignalPoints; i++)
+ output[i] = convolve (input, m_signalInc, i, m_nSignalPoints);
+ } else if (m_idFilterMethod == FILTER_METHOD_FOURIER) {
+ double inputSignal[m_nFilterPoints];
+ for (int i = 0; i < m_nSignalPoints; i++)
+ inputSignal[i] = input[i];
+ for (int i = m_nSignalPoints; i < m_nFilterPoints; i++)
+ inputSignal[i] = 0; // zeropad
+ complex<double> fftSignal[m_nFilterPoints];
+ finiteFourierTransform (inputSignal, fftSignal, m_nFilterPoints, -1);
+ for (int i = 0; i < m_nFilterPoints; i++)
+ fftSignal[i] *= m_vecFilter[i];
+ double inverseFourier[m_nFilterPoints];
+ finiteFourierTransform (fftSignal, inverseFourier, m_nFilterPoints, 1);
+ for (int i = 0; i < m_nSignalPoints; i++)
+ output[i] = inverseFourier[i];
+ } else if (m_idFilterMethod == FILTER_METHOD_FOURIER_TABLE) {
+ double inputSignal[m_nFilterPoints];
+ for (int i = 0; i < m_nSignalPoints; i++)
+ inputSignal[i] = input[i];
+ for (int i = m_nSignalPoints; i < m_nFilterPoints; i++)
+ inputSignal[i] = 0; // zeropad
+ complex<double> fftSignal[m_nFilterPoints];
+ finiteFourierTransform (inputSignal, fftSignal, -1);
+ for (int i = 0; i < m_nFilterPoints; i++)
+ fftSignal[i] *= m_vecFilter[i];
+ double inverseFourier[m_nFilterPoints];
+ finiteFourierTransform (fftSignal, inverseFourier, 1);
+ for (int i = 0; i < m_nSignalPoints; i++)
+ output[i] = inverseFourier[i];
+ }
+#if HAVE_FFTW
+ else if (m_idFilterMethod == FILTER_METHOD_RFFTW) {
+ for (int i = 0; i < m_nSignalPoints; i++)
+ m_vecRealFftInput[i] = input[i];
+
+ fftw_real fftOutput [ m_nFilterPoints ];
+ rfftw_one (m_realPlanForward, m_vecRealFftInput, fftOutput);
+ for (int i = 0; i < m_nFilterPoints; i++)
+ m_vecRealFftSignal[i] = m_vecFilter[i] * fftOutput[i];
+ for (int i = m_nFilterPoints; i < m_nOutputPoints; i++)
+ m_vecRealFftSignal[i] = 0;
+
+ fftw_real ifftOutput [ m_nOutputPoints ];
+ rfftw_one(m_realPlanBackward, m_vecRealFftSignal, ifftOutput);
+ for (int i = 0; i < m_nSignalPoints * m_preinterpolationFactor; i++)
+ output[i] = ifftOutput[i];
+ } else if (m_idFilterMethod == FILTER_METHOD_FFTW) {
+ for (int i = 0; i < m_nSignalPoints; i++)
+ m_vecComplexFftInput[i].re = input[i];
+
+ fftw_complex fftOutput [ m_nFilterPoints ];
+ fftw_one(m_complexPlanForward, m_vecComplexFftInput, fftOutput);
+ for (int i = 0; i < m_nFilterPoints; i++) {
+ m_vecComplexFftSignal[i].re = m_vecFilter[i] * fftOutput[i].re;
+ m_vecComplexFftSignal[i].im = m_vecFilter[i] * fftOutput[i].im;
+ }
+ fftw_complex ifftOutput [ m_nOutputPoints ];
+ fftw_one(m_complexPlanBackward, m_vecComplexFftSignal, ifftOutput);
+ for (int i = 0; i < m_nSignalPoints * m_preinterpolationFactor; i++)
+ output[i] = ifftOutput[i].re;
+ }
+#endif
+}
double
SignalFilter::response (double x)
double response = 0;
if (m_idDomain == DOMAIN_SPATIAL)
- response = spatialResponse (m_idFilter, m_bw, x, m_filterParam, m_numIntegral);
- else if (m_idDomain == DOMAIN_FREQ)
+ response = spatialResponse (m_idFilter, m_bw, x, m_filterParam);
+ else if (m_idDomain == DOMAIN_FREQUENCY)
response = frequencyResponse (m_idFilter, m_bw, x, m_filterParam);
return (response);
double
-SignalFilter::spatialResponse (FilterID filterID, double bw, double x, double param, int nIntegral = 0)
+SignalFilter::spatialResponse (FilterID filterID, double bw, double x, double param)
{
- if (nIntegral == 0)
+ if (haveAnalyticSpatial(filterID))
return spatialResponseAnalytic (filterID, bw, x, param);
else
- return spatialResponseCalc (filterID, bw, x, param, nIntegral);
+ return spatialResponseCalc (filterID, bw, x, param, N_INTEGRAL);
}
/* NAME
*/
double
-SignalFilter::spatialResponseCalc (double x, double param, int nIntegral) const
+SignalFilter::spatialResponseCalc (double x, double param) const
{
- return (spatialResponseCalc (m_idFilter, m_bw, x, param, nIntegral));
+ return (spatialResponseCalc (m_idFilter, m_bw, x, param, N_INTEGRAL));
}
double
return spatialResponseAnalytic (m_idFilter, m_bw, x, param);
}
+const bool
+SignalFilter::haveAnalyticSpatial (FilterID filterID)
+{
+ bool haveAnalytic = false;
+
+ switch (filterID) {
+ case FILTER_BANDLIMIT:
+ case FILTER_TRIANGLE:
+ case FILTER_COSINE:
+ case FILTER_G_HAMMING:
+ case FILTER_ABS_BANDLIMIT:
+ case FILTER_ABS_COSINE:
+ case FILTER_ABS_G_HAMMING:
+ case FILTER_SHEPP:
+ case FILTER_SINC:
+ haveAnalytic = true;
+ break;
+ default:
+ break;
+ }
+
+ return (haveAnalytic);
+}
+
double
SignalFilter::spatialResponseAnalytic (FilterID filterID, double bw, double x, double param)
{
double
SignalFilter::integral_abscos (double u, double w)
{
- if (fabs (u) > F_EPSILON)
- return (cos(u * w) - 1) / (u * u) + w / u * sin (u * w);
- else
- return (w * w / 2);
+ return (fabs (u) > F_EPSILON
+ ? (cos(u * w) - 1) / (u * u) + w / u * sin (u * w)
+ : (w * w / 2));
}
return (sum * dx);
}
+
+void
+SignalFilter::finiteFourierTransform (const double input[], complex<double> output[], const int n, int direction)
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ double angleIncrement = direction * 2 * PI / n;
+ for (int i = 0; i < n; i++) {
+ double sumReal = 0;
+ double sumImag = 0;
+ for (int j = 0; j < n; j++) {
+ double angle = i * j * angleIncrement;
+ sumReal += input[j] * cos(angle);
+ sumImag += input[j] * sin(angle);
+ }
+ if (direction < 0) {
+ sumReal /= n;
+ sumImag /= n;
+ }
+ output[i] = complex<double> (sumReal, sumImag);
+ }
+}
+
+
+void
+SignalFilter::finiteFourierTransform (const complex<double> input[], complex<double> output[], const int n, int direction)
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ double angleIncrement = direction * 2 * PI / n;
+ for (int i = 0; i < n; i++) {
+ complex<double> sum (0,0);
+ for (int j = 0; j < n; j++) {
+ double angle = i * j * angleIncrement;
+ complex<double> exponentTerm (cos(angle), sin(angle));
+ sum += input[j] * exponentTerm;
+ }
+ if (direction < 0) {
+ sum /= n;
+ }
+ output[i] = sum;
+ }
+}
+
+void
+SignalFilter::finiteFourierTransform (const complex<double> input[], double output[], const int n, int direction)
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ double angleIncrement = direction * 2 * PI / n;
+ for (int i = 0; i < n; i++) {
+ double sumReal = 0;
+ for (int j = 0; j < n; j++) {
+ double angle = i * j * angleIncrement;
+ sumReal += input[j].real() * cos(angle) - input[j].imag() * sin(angle);
+ }
+ if (direction < 0) {
+ sumReal /= n;
+ }
+ output[i] = sumReal;
+ }
+}
+
+void
+SignalFilter::finiteFourierTransform (const double input[], complex<double> output[], int direction) const
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ for (int i = 0; i < m_nFilterPoints; i++) {
+ double sumReal = 0, sumImag = 0;
+ for (int j = 0; j < m_nFilterPoints; j++) {
+ int tableIndex = i * j;
+ if (direction > 0) {
+ sumReal += input[j] * m_vecFourierCosTable[tableIndex];
+ sumImag += input[j] * m_vecFourierSinTable[tableIndex];
+ } else {
+ sumReal += input[j] * m_vecFourierCosTable[tableIndex];
+ sumImag -= input[j] * m_vecFourierSinTable[tableIndex];
+ }
+ }
+ if (direction < 0) {
+ sumReal /= m_nFilterPoints;
+ sumImag /= m_nFilterPoints;
+ }
+ output[i] = complex<double> (sumReal, sumImag);
+ }
+}
+
+// (a+bi) * (c + di) = (ac - bd) + (ad + bc)i
+void
+SignalFilter::finiteFourierTransform (const complex<double> input[], complex<double> output[], int direction) const
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ for (int i = 0; i < m_nFilterPoints; i++) {
+ double sumReal = 0, sumImag = 0;
+ for (int j = 0; j < m_nFilterPoints; j++) {
+ int tableIndex = i * j;
+ if (direction > 0) {
+ sumReal += input[j].real() * m_vecFourierCosTable[tableIndex]
+ - input[j].imag() * m_vecFourierSinTable[tableIndex];
+ sumImag += input[j].real() * m_vecFourierSinTable[tableIndex]
+ + input[j].imag() * m_vecFourierCosTable[tableIndex];
+ } else {
+ sumReal += input[j].real() * m_vecFourierCosTable[tableIndex]
+ - input[j].imag() * -m_vecFourierSinTable[tableIndex];
+ sumImag += input[j].real() * -m_vecFourierSinTable[tableIndex]
+ + input[j].imag() * m_vecFourierCosTable[tableIndex];
+ }
+ }
+ if (direction < 0) {
+ sumReal /= m_nFilterPoints;
+ sumImag /= m_nFilterPoints;
+ }
+ output[i] = complex<double> (sumReal, sumImag);
+ }
+}
+
+void
+SignalFilter::finiteFourierTransform (const complex<double> input[], double output[], int direction) const
+{
+ if (direction < 0)
+ direction = -1;
+ else
+ direction = 1;
+
+ for (int i = 0; i < m_nFilterPoints; i++) {
+ double sumReal = 0;
+ for (int j = 0; j < m_nFilterPoints; j++) {
+ int tableIndex = i * j;
+ if (direction > 0) {
+ sumReal += input[j].real() * m_vecFourierCosTable[tableIndex]
+ - input[j].imag() * m_vecFourierSinTable[tableIndex];
+ } else {
+ sumReal += input[j].real() * m_vecFourierCosTable[tableIndex]
+ - input[j].imag() * -m_vecFourierSinTable[tableIndex];
+ }
+ }
+ if (direction < 0) {
+ sumReal /= m_nFilterPoints;
+ }
+ output[i] = sumReal;
+ }
+}
+
+
projects / ctsim.git / blobdiff