What is the RFFT and iRFFT complexity?

1. What is the difference between FFT and RFFT?
2. What is Rfft in Python?
3. What does RFFT return?
4. What is a real FFT?

What is the difference between FFT and RFFT?

fft() accepts complex-valued input, and rfft() accepts real-valued input.

What is Rfft in Python?

numpy.fft.rfft(a, n=None, axis=-1)[source] Compute the one-dimensional discrete Fourier Transform for real input. This function computes the one-dimensional n-point discrete Fourier Transform (DFT) of a real-valued array by means of an efficient algorithm called the Fast Fourier Transform (FFT).

What does RFFT return?

FFT returns a complex array that has the same dimensions as the input array. The output array is ordered in the same manner as almost all discrete Fourier transforms. Element 0 contains the zero frequency component, F₀.

What is a real FFT?

The real portion of an FFT result is how much each frequency component resembles a cosine wave, the imaginary component, how much each component resembles a sine wave.