fftN

PlasmaCalcs.tools.fft_tools.array_fft.fftN(array, ds, axes=None, *, rad=False, **kw_np_fftn)

calculates fft along N dimensions, as well as the corresponding frequencies.

array: array-like

take the fft of this array (along the indicated axes).

ds: list-like with length == len(axes) (or array.ndim if axes is None)

specifies the spacing between elements of array (in position-space), along each axis.

This is necessary in order to provide the frequency coordinates for the result.

axes: None, or iterable of ints

axes to take fft over. (Negative values are supported & count from end.)

None –> take fft over all axes.

rad: bool

if True, convert frequencies to “radians” by multiplying them by 2 * pi.

E.g., for fft in space, rad=False gives 1/wavelength; rad=True gives wavenumber k.

additional kwargs passed to np.fft.fftn.

returns (shifted fftn(array, axes=axes, **kw_np_fftn), (freq0, freq1, …, freqN)),

where freq0, freq1, …, freqN are the frequencies corresponding to the N axes,

and all freqs & values are shifted with np.fft.fftshift to put the 0-frequency in the center.