Compute the N-dimensional Fast Fourier Transform.
a : array_like
s : sequence of ints
axes : tuple of int
Analogously to fft, the term for zero frequency in all axes is in the low-order corner, while the term for the Nyquist frequency in all axes is in the middle.
If neither s nor axes is specified, the transform is taken along all axes. If s is specified and axes is not, the last len(s) axes are used. If axes is specified and s is not, the input shape along the specified axes is used. If s and axes are both specified and are not the same length, an exception is raised.