fft_in_place
Copyright (C) 2005 IENT-RWTH Aachen
template<class G> inline void fft_in_place(Vector<G> &X)
FFT in place of a signal
Parameters
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The FFT |
Remarks
For complex signal, this function is equivalent to fft(X,X).
The FFT of a real signal with N terms is complex and has the following symmetry property:
Y[N-i] = conj(Y[i])
The arrangement of the compact half-complex terms uses the following scheme:
k = 0 | X[k] = real(Y[k]), imaginary part is zero and not stored |
k < N/2 | X[k] = real(Y[k]), X[N-k] = imag(Y[k]) |
k = N/2 | X[k] = real(Y[k]), imaginary part is zero and not stored |
k > N/2 | Terms not stored but can be reconstructed using the symmetry property. |
Example
DenseVector<float>::self X(4, 1); fft_in_place(X);