Re: WG: [PD] fft algorithms

hi Thomas,

it looks like your 2nd requirement is met for rfftw:

``FFTW's one-dimensional real transforms store hermitian arrays as "halfcomplex" arrays. A halfcomplex array of size n is a one-dimensional array of n `fftw_real' numbers. A hermitian array X in stored into a halfcomplex array Y as follows. For all integers i such that 0 <= i <= n / 2, we have Y[i] = Re(X[i]). For all integers i such that 0 < i < n / 2, we have Y[n-i] = Im(X[i]).''

The actual `real2hc' codelets use separate real and imag arrays.

Krzysztof

Thomas Grill wrote: ...

following properties:

• in-place (or with a small workspace)
• separated vectors for real and imaginary data, with stride factors
• preferably also mixed-radix (for non-power-2 transforms)

Alternatively, as FFTW exists (but doesn't fulfill the 2nd requirement):

• is there an algorithm that transforms a vector of complex points into

separated real and imaginary vectors in place?