Module microfft::real

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FFT on real inputs (RFFT)

This implementation takes advantage of the symmetry properties of the FFT to compute an N-point RFFT by internally invoking an N/2-point CFFT, roughly doubling the computation speed compared to used a full N-point CFFT.

The produced output is the first half out the output returned by the corresponding N-point CFFT, i.e. the real DC value and N/2 - 1 positive-frequency terms. Additionally, the real-valued coefficient at the Nyquist frequency is packed into the imaginary part of the DC bin. The negative-frequency terms are not computed, since they can be calculated from the positive-frequency terms and are therefore redundant.

Functions§

  • rfft_2
    Perform an in-place 2-point RFFT.
  • rfft_4
    Perform an in-place 4-point RFFT.
  • rfft_8
    Perform an in-place 8-point RFFT.
  • rfft_16
    Perform an in-place 16-point RFFT.
  • rfft_32
    Perform an in-place 32-point RFFT.
  • rfft_64
    Perform an in-place 64-point RFFT.
  • rfft_128
    Perform an in-place 128-point RFFT.
  • rfft_256
    Perform an in-place 256-point RFFT.
  • rfft_512
    Perform an in-place 512-point RFFT.
  • rfft_1024
    Perform an in-place 1024-point RFFT.
  • rfft_2048
    Perform an in-place 2048-point RFFT.
  • rfft_4096
    Perform an in-place 4096-point RFFT.
  • rfft_8192
    Perform an in-place 8192-point RFFT.