reserved for passing in a precomputed plan provided
    by downstream FFT vendors. It is currently not used in SciPy.

    .. versionadded:: 1.5.0

Returns
-------
out : ndarray
    The truncated or zero-padded input, transformed along the axes
    indicated by `axes`, or by a combination of `s` or `x`,
    as explained in the parameters section above.
    The length of each transformed axis is as given by the corresponding
    element of `s`, or the length of the input in every axis except for the
    last one if `s` is not given. In the final transformed axis the length
    of the output when `s` is not given is ``2*(m-1)``, where ``m`` is the
    length of the final transformed axis of the input. To get an odd
    number of output points in the final axis, `s` must be specified.

Raises
------
ValueError
    If `s` and `axes` have different length.
IndexError
    If an element of `axes` is larger than the number of axes of `x`.

See Also
--------
rfftn : The forward N-D FFT of real input,
        of which `ifftn` is the inverse.
fft : The 1-D FFT, with definitions and conventions used.
irfft : The inverse of the 1-D FFT of real input.
irfft2 : The inverse of the 2-D FFT of real input.

Notes
-----
See `fft` for definitions and conventions used.

See `rfft` for definitions and conventions used for real input.

The default value of `s` assumes an even output length in the final
transformation axis. When performing the final complex to real
transformation, the Hermitian symmetry requires that the last imaginary
component along that axis must be 0 and so it is ignored. To avoid losing
information, the correct length of the real input *must* be given.

Examples
--------
>>> import scipy.fft
>>> import numpy as np
>>> x = np.zeros((3, 2, 2))
>>> x[0, 0, 0] = 3 * 2 * 2
>>> scipy.fft.irfftn(x)
array([[[1.,  1.],
        [1.,  1.]],
       [[1.,  1.],
        [1.,  1.]],
       [[1.,  1.],
        [1.,  1.]]])

r