FFT(double[] x, double[] y, uint n, FourierDirection direction, ref object temporaryStorage)
{
ChirpNativeFFTStorage s = temporaryStorage as ChirpNativeFFTStorage;
chirpnativefft(x, y, x, y, (int)n, direction, ref s);
temporaryStorage = s;
}
FourierTransformation2D(IMatrix <double> matrixRe, IMatrix <double> matrixIm, FourierDirection direction)
{
int numberOfRows = matrixRe.RowCount;
int numberOfColumns = matrixRe.ColumnCount;
// Do the FFT in the first direction
// First direction: transform all columns of the matrix
ChirpNativeFFTStorage tempStorage = null;
var resultArrayRe = new double[numberOfRows];
var resultArrayIm = new double[numberOfRows];
var inputArrayRe = new double[numberOfRows];
var inputArrayIm = new double[numberOfRows];
for (int c = 0; c < numberOfColumns; ++c) // for each column
{
for (int r = 0; r < numberOfRows; ++r)
{
inputArrayRe[r] = matrixRe[r, c];
inputArrayIm[r] = matrixIm[r, c];
}
chirpnativefft(resultArrayRe, resultArrayIm, inputArrayRe, inputArrayIm, numberOfRows, direction, ref tempStorage);
for (int r = 0; r < numberOfRows; ++r)
{
matrixRe[r, c] = resultArrayRe[r];
matrixIm[r, c] = resultArrayIm[r];
}
}
// Second direction: transform all rows of the matrix
if (numberOfColumns != numberOfRows)
{
resultArrayRe = new double[numberOfColumns];
resultArrayIm = new double[numberOfColumns];
inputArrayRe = new double[numberOfColumns];
inputArrayIm = new double[numberOfColumns];
}
for (int r = 0; r < numberOfRows; ++r) // for each row
{
for (int c = 0; c < numberOfColumns; ++c)
{
inputArrayRe[c] = matrixRe[r, c];
inputArrayIm[c] = matrixIm[r, c];
}
chirpnativefft(resultArrayRe, resultArrayIm, inputArrayRe, inputArrayIm, numberOfColumns, direction, ref tempStorage);
for (int c = 0; c < numberOfColumns; ++c)
{
matrixRe[r, c] = resultArrayRe[c];
matrixIm[r, c] = resultArrayIm[c];
}
}
}
private static void chirpnativefft(
double[] resultreal,
double[] resultimag,
double[] inputreal,
double[] inputimag,
int arrsize,
FourierDirection direction,
ref ChirpNativeFFTStorage s)
{
if (arrsize <= 2)
{
throw new ArgumentException("This algorithm works for array sizes > 2 only.");
}
int msize = GetNecessaryTransformationSize(arrsize);
if (s == null || arrsize != s._arrSize || direction != s._direction)
{
s = new ChirpNativeFFTStorage(msize, arrsize, direction);
}
else // if the temp storage is not fresh, we have to clear the arrays first
{
Array.Clear(s._xjfj_real, 0, msize);
Array.Clear(s._xjfj_imag, 0, msize);
}
// make the arrays local variables
double[] xjfj_real = s._xjfj_real;
double[] xjfj_imag = s._xjfj_imag;
double[] fserp_real = s._fserp_real;
double[] fserp_imag = s._fserp_imag;
double[] resarray_real = s._resarray_real;
double[] resarray_imag = s._resarray_imag;
var chirpfactor_real = s._chirpfactors_real;
var chirpfactor_imag = s._chirpfactors_imag;
// multiply the input array with the chirpfactors
for (int i = 0; i < arrsize; ++i)
{
xjfj_real[i] = inputreal[i] * chirpfactor_real[i] - inputimag[i] * chirpfactor_imag[i];
xjfj_imag[i] = inputreal[i] * chirpfactor_imag[i] + inputimag[i] * chirpfactor_real[i];
}
// convolute xjfj with precomputed fourier-transformation of fserp
fhtconvolutionWithFouriertransformed2ndArgument(resarray_real, resarray_imag, xjfj_real, xjfj_imag, fserp_real, fserp_imag, msize);
// multiply the result with the chirpfactors
for (int i = 0; i < arrsize; ++i)
{
resultreal[i] = resarray_real[i] * chirpfactor_real[i] - resarray_imag[i] * chirpfactor_imag[i];
resultimag[i] = resarray_real[i] * chirpfactor_imag[i] + resarray_imag[i] * chirpfactor_real[i];
}
}
FFT(double[] x, double[] y, FourierDirection direction, ref object temporaryStorage)
{
if (x.Length != y.Length)
{
throw new ArgumentException("Length of real and imaginary array do not match!");
}
ChirpNativeFFTStorage s = temporaryStorage as ChirpNativeFFTStorage;
chirpnativefft(x, y, x, y, x.Length, direction, ref s);
temporaryStorage = s;
}
private static void chirpnativefft(
double[] resultreal,
double[] resultimag,
double[] inputreal,
double[] inputimag,
int arrsize,
FourierDirection direction,
ref ChirpNativeFFTStorage s)
{
int phasesign = direction == FourierDirection.Forward ? 1 : -1;
int arrsize2 = arrsize + arrsize;
if (arrsize <= 2)
{
throw new ArgumentException("This algorithm works for array sizes > 2 only.");
}
int msize = GetNecessaryTransformationSize(arrsize);
if (s == null || s.Length != msize)
{
s = new ChirpNativeFFTStorage(msize);
}
double[] xjfj_real = s.xjfj_real;
double[] xjfj_imag = s.xjfj_imag;
double[] fserp_real = s.fserp_real;
double[] fserp_imag = s.fserp_imag;
double[] resarray_real = s.resarray_real;
double[] resarray_imag = s.resarray_imag;
// bilde xj*fj
double prefactor = phasesign * Math.PI / arrsize;
int np = 0;
for (int i = 0; i < arrsize; i++)
{
double phi = prefactor * np; // np should be equal to (i*i)%arrsize2
double vre = Math.Cos(phi);
double vim = Math.Sin(phi);
xjfj_real[i] = inputreal[i] * vre - inputimag[i] * vim;
xjfj_imag[i] = inputreal[i] * vim + inputimag[i] * vre;
np += i + i + 1; // np == (k*k)%n2
if (np >= arrsize2)
{
np -= arrsize2;
}
}
// fill positive and negative part of fserp
fserp_real[0] = 1; fserp_imag[0] = 0;
prefactor = -phasesign * Math.PI / arrsize;
np = 1; // since we start the loop with 1
for (int i = 1; i < arrsize; i++)
{
double phi = prefactor * np; // np should be equal to (i*i)%arrsize2
fserp_real[i] = fserp_real[msize - i] = Math.Cos(phi);
fserp_imag[i] = fserp_imag[msize - i] = Math.Sin(phi);
np += i + i + 1; // np == (k*k)%n2
if (np >= arrsize2)
{
np -= arrsize2;
}
}
// convolute xjfj with fserp
//NativeCyclicConvolution(resarray,xjfj,fserp,msize);
fhtconvolution(resarray_real, resarray_imag, xjfj_real, xjfj_imag, fserp_real, fserp_imag, msize);
// multipliziere mit fserpschlange
prefactor = phasesign * Math.PI / arrsize;
np = 0;
for (int i = 0; i < arrsize; i++)
{
double phi = prefactor * np; // np should be equal to (i*i)%arrsize2
double vre = Math.Cos(phi);
double vim = Math.Sin(phi);
resultreal[i] = resarray_real[i] * vre - resarray_imag[i] * vim;
resultimag[i] = resarray_real[i] * vim + resarray_imag[i] * vre;
np += i + i + 1; // np == (i*i)%n2
if (np >= arrsize2)
{
np -= arrsize2;
}
}
}
private static void chirpnativefft(
double[] resultreal,
double[] resultimag,
double[] inputreal,
double[] inputimag,
int arrsize,
FourierDirection direction,
ref ChirpNativeFFTStorage s)
{
if (arrsize <= 2)
throw new ArgumentException("This algorithm works for array sizes > 2 only.");
int msize = GetNecessaryTransformationSize(arrsize);
if (s == null || arrsize != s._arrSize || direction != s._direction)
{
s = new ChirpNativeFFTStorage(msize, arrsize, direction);
}
else // if the temp storage is not fresh, we have to clear the arrays first
{
Array.Clear(s._xjfj_real, 0, msize);
Array.Clear(s._xjfj_imag, 0, msize);
}
// make the arrays local variables
double[] xjfj_real = s._xjfj_real;
double[] xjfj_imag = s._xjfj_imag;
double[] fserp_real = s._fserp_real;
double[] fserp_imag = s._fserp_imag;
double[] resarray_real = s._resarray_real;
double[] resarray_imag = s._resarray_imag;
var chirpfactor_real = s._chirpfactors_real;
var chirpfactor_imag = s._chirpfactors_imag;
// multiply the input array with the chirpfactors
for (int i = 0; i < arrsize; ++i)
{
xjfj_real[i] = inputreal[i] * chirpfactor_real[i] - inputimag[i] * chirpfactor_imag[i];
xjfj_imag[i] = inputreal[i] * chirpfactor_imag[i] + inputimag[i] * chirpfactor_real[i];
}
// convolute xjfj with precomputed fourier-transformation of fserp
fhtconvolutionWithFouriertransformed2ndArgument(resarray_real, resarray_imag, xjfj_real, xjfj_imag, fserp_real, fserp_imag, msize);
// multiply the result with the chirpfactors
for (int i = 0; i < arrsize; ++i)
{
resultreal[i] = resarray_real[i] * chirpfactor_real[i] - resarray_imag[i] * chirpfactor_imag[i];
resultimag[i] = resarray_real[i] * chirpfactor_imag[i] + resarray_imag[i] * chirpfactor_real[i];
}
}
private static void chirpnativefft(
double[] resultreal,
double[] resultimag,
double[] inputreal,
double[] inputimag,
int arrsize,
FourierDirection direction,
ref ChirpNativeFFTStorage s)
{
int phasesign = direction==FourierDirection.Forward ? 1 : -1;
int arrsize2 = arrsize+arrsize;
if(arrsize<=2)
throw new ArgumentException("This algorithm works for array sizes > 2 only.");
int msize = GetNecessaryTransformationSize(arrsize);
if(s==null || s.Length!=msize)
{
s = new ChirpNativeFFTStorage(msize);
}
double[] xjfj_real = s.xjfj_real;
double[] xjfj_imag = s.xjfj_imag;
double[] fserp_real = s.fserp_real;
double[] fserp_imag = s.fserp_imag;
double[] resarray_real = s.resarray_real;
double[] resarray_imag = s.resarray_imag;
// bilde xj*fj
double prefactor = phasesign * Math.PI / arrsize;
int np = 0;
for(int i=0;i<arrsize;i++)
{
double phi = prefactor*np; // np should be equal to (i*i)%arrsize2
double vre = Math.Cos(phi);
double vim = Math.Sin(phi);
xjfj_real[i] = inputreal[i] * vre - inputimag[i] * vim;
xjfj_imag[i] = inputreal[i] * vim + inputimag[i] * vre;
np += i+i+1; // np == (k*k)%n2
if ( np >= arrsize2 )
np -= arrsize2;
}
// fill positive and negative part of fserp
fserp_real[0]=1; fserp_imag[0]=0;
prefactor = -phasesign * Math.PI / arrsize;
np = 1; // since we start the loop with 1
for(int i=1;i<arrsize;i++)
{
double phi = prefactor * np; // np should be equal to (i*i)%arrsize2
fserp_real[i] = fserp_real[msize-i] = Math.Cos(phi);
fserp_imag[i] = fserp_imag[msize-i] = Math.Sin(phi);
np += i+i+1; // np == (k*k)%n2
if ( np >= arrsize2 )
np -= arrsize2;
}
// convolute xjfj with fserp
//NativeCyclicConvolution(resarray,xjfj,fserp,msize);
fhtconvolution(resarray_real,resarray_imag,xjfj_real,xjfj_imag,fserp_real,fserp_imag,msize);
// multipliziere mit fserpschlange
prefactor = phasesign * Math.PI / arrsize;
np = 0;
for(int i=0;i<arrsize;i++)
{
double phi = prefactor * np; // np should be equal to (i*i)%arrsize2
double vre = Math.Cos(phi);
double vim = Math.Sin(phi);
resultreal[i] = resarray_real[i]*vre - resarray_imag[i]*vim;
resultimag[i] = resarray_real[i]*vim + resarray_imag[i]*vre;
np += i+i+1; // np == (i*i)%n2
if ( np >= arrsize2 )
np -= arrsize2;
}
}
