package owl

``fft ~axis x`` performs 1-dimensional FFT on a complex input. ``axis`` is the highest dimension if not specified. The return is not scaled.

``ifft ~axis x`` performs inverse 1-dimensional FFT on a complex input. ``axis`` is the highest dimension by default.

``rfft ~axis ~otyp x`` performs 1-dimensional FFT on real input along the ``axis``. ``otyp`` is used to specify the output type, it must be the consistent precision with input ``x``. You can skip this parameter by using a submodule with specific precision such as ``Owl.Fft.S`` or ``Owl.Fft.D``.

``irfft ~axis ~n x`` is the inverse function of ``rfft``. Note the ``n`` parameter is used to specified the size of output.