s the length of the transformed axis of the
    input. To get an odd number of output points, `n` must be specified.

Raises
------
IndexError
    If `axis` is larger than the last axis of `x`.

See Also
--------
rfft : The 1-D FFT of real input, of which `irfft` is inverse.
fft : The 1-D FFT.
irfft2 : The inverse of the 2-D FFT of real input.
irfftn : The inverse of the N-D FFT of real input.

Notes
-----
Returns the real valued `n`-point inverse discrete Fourier transform
of `x`, where `x` contains the non-negative frequency terms of a
Hermitian-symmetric sequence. `n` is the length of the result, not the
input.

If you specify an `n` such that `a` must be zero-padded or truncated, the
extra/removed values will be added/removed at high frequencies. One can
thus resample a series to `m` points via Fourier interpolation by:
``a_resamp = irfft(rfft(a), m)``.

The default value of `n` assumes an even output length. By the Hermitian
symmetry, the last imaginary component must be 0 and so is ignored. To
avoid losing information, the correct length of the real input *must* be
given.

Examples
--------
>>> import scipy.fft
>>> scipy.fft.ifft([1, -1j, -1, 1j])
array([0.+0.j,  1.+0.j,  0.+0.j,  0.+0.j]) # may vary
>>> scipy.fft.irfft([1, -1j, -1])
array([0.,  1.,  0.,  0.])

Notice how the last term in the input to the ordinary `ifft` is the
complex conjugate of the second term, and the output has zero imaginary
part everywhere. When calling `irfft`, the negative frequencies are not
specified, and the output array is purely real.

r