fftw3d {fftwtools}

Compute a two-dimensional FFT on a matrix using FFTW3

Description

Computes three-dimensional FFT on an array using the FFTW3 libraries. Use fftw_r2c_3d(x, HermConj=0) for real to complex FFT. This will return the result without the "Hermitian" redundancy. These functions follow the R convention when returning the inverse of the FFT. For the two-dimension fft, the inverse is currently requires the entire matrix, including the redundant complex conjugate.

Usage

fftw3d(data, inverse=0, HermConj=1)
fftw_r2c_3d(data, HermConj=1)
fftw_c2c_3d(data, inverse=0)

Arguments

data

(complex or real) 3-dimensional array to be processed

inverse

(integer) 1 or 0 indicating if inverse FFT is preformed. The return follows the format of the R FFT commands–the output is not scaled.

HermConj

(integer) 1 or 0 indicating if either "Hermitian" redundant conjugate should be returned.

Author(s)

Karim Rahim

Examples

x=c(1, 2, 3, 9, 8, 5, 1, 2, 9, 8, 7, 2)
x= array(x, dim=c(3,2,2))

fftw3d(x)
fftw3d(x, HermConj=0)

fftw3d(fftw3d(x), inverse=1)/12

fftw_r2c_3d(x)
fftw_r2c_3d(x, HermConj=0)