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added FFT inverse complex-to-scalar interface (not yet optimized)

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This commit is contained in:
Mark Borgerding
2009-05-23 22:50:07 -04:00
parent 3047988172
commit 326ea77390
3 changed files with 81 additions and 44 deletions
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31
unsupported/Eigen/src/FFT/simple_fft_traits.h
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@@ -54,28 +54,14 @@ namespace Eigen {
work(0, dst, src, 1,1);
}else{
int ncfft = nfft>>1;
int ncfft2 = nfft>>2;
// use optimized mode for even real
fwd( dst, reinterpret_cast<const Complex*> (src),ncfft);
make_real_twiddles(nfft);
std::cerr << "dst[0] = " << dst[0] << "\n";
Complex dc = dst[0].real() + dst[0].imag();
Complex nyquist = dst[0].real() - dst[0].imag();
int k;
#if 0
using namespace std;
cerr << "desired:\n";
for ( k=1;k <= (ncfft>>1) ; ++k ) {
Complex x = exp( Complex(0,-3.14159265358979323846264338327 * ((double) (k) / ncfft + .5) ) );
cerr << k << " " << x << "angle(x):" << arg(x) << "\n";
}
dc=0;
cerr << "twiddles:\n";
for (k=0;k<ncfft;++k) {
Complex x = m_twiddles[k];
cerr << k << " " << x << "angle(-x):" << arg(-x) << "\n";
}
#endif
for ( k=1;k <= (ncfft>>1) ; ++k ) {
for ( k=1;k <= ncfft2 ; ++k ) {
Complex fpk = dst[k];
Complex fpnk = conj(dst[ncfft-k]);
Complex f1k = fpk + fpnk;
@@ -87,7 +73,6 @@ namespace Eigen {
dst[ncfft-k] = conj(f1k -tw)*Scalar(.5);
}
// place conjugate-symmetric half at the end for completeness
// TODO: make this configurable ( opt-out )
for ( k=1;k < ncfft ; ++k )
@@ -98,6 +83,16 @@ namespace Eigen {
}
}
// half-complex to scalar
void inv( Scalar * dst,const Complex * src,int nfft)
{
// TODO add optimized version for even numbers
std::vector<Complex> tmp(nfft);
inv(&tmp[0],src,nfft);
for (int k=0;k<nfft;++k)
dst[k] = tmp[k].real();
}
void inv(Complex * dst,const Complex *src,int nfft)
{
prepare(nfft,true);
@@ -156,7 +151,7 @@ namespace Eigen {
default: p += 2; break;
}
if (p*p>n)
p=n;// no more factors
p=n;// impossible to have a factor > sqrt(n)
}
n /= p;
m_stageRadix.push_back(p);