To cite package ‘fftw’ in publications use:

Mersmann O (2024). fftw: Fast FFT and DCT Based on the FFTW Library. R package version 1.0-9, https://CRAN.R-project.org/package=fftw.

Corresponding BibTeX entry:

  @Manual{,
    title = {fftw: Fast FFT and DCT Based on the FFTW Library},
    author = {Olaf Mersmann},
    year = {2024},
    note = {R package version 1.0-9},
    url = {https://CRAN.R-project.org/package=fftw},
  }