# Discrete Fourier Transform¶

## Standard FFTs¶

 `mars.tensor.fft.fft` Compute the one-dimensional discrete Fourier Transform. `mars.tensor.fft.ifft` Compute the one-dimensional inverse discrete Fourier Transform. `mars.tensor.fft.fft2` Compute the 2-dimensional discrete Fourier Transform `mars.tensor.fft.ifft2` Compute the 2-dimensional inverse discrete Fourier Transform. `mars.tensor.fft.fftn` Compute the N-dimensional discrete Fourier Transform. `mars.tensor.fft.ifftn` Compute the N-dimensional inverse discrete Fourier Transform.

## Real FFTs¶

 `mars.tensor.fft.rfft` Compute the one-dimensional discrete Fourier Transform for real input. `mars.tensor.fft.irfft` Compute the inverse of the n-point DFT for real input. `mars.tensor.fft.rfft2` Compute the 2-dimensional FFT of a real tensor. `mars.tensor.fft.irfft2` Compute the 2-dimensional inverse FFT of a real array. `mars.tensor.fft.rfftn` Compute the N-dimensional discrete Fourier Transform for real input. `mars.tensor.fft.irfftn` Compute the inverse of the N-dimensional FFT of real input.

## Hermitian FFTs¶

 `mars.tensor.fft.hfft` Compute the FFT of a signal that has Hermitian symmetry, i.e., a real spectrum. `mars.tensor.fft.ihfft` Compute the inverse FFT of a signal that has Hermitian symmetry.

## Helper routines¶

 `mars.tensor.fft.fftfreq` Return the Discrete Fourier Transform sample frequencies. `mars.tensor.fft.rfftfreq` Return the Discrete Fourier Transform sample frequencies (for usage with rfft, irfft). `mars.tensor.fft.fftshift` Shift the zero-frequency component to the center of the spectrum. `mars.tensor.fft.ifftshift` The inverse of fftshift.