Compute the onedimensonal inverse fft along an axis.
Return the n point inverse discrete Fourier transform of a. The length n defaults to the length of a. If n is larger than the length of a, then a will be zeropadded to make up the difference. If n is smaller than the length of a, then a will be truncated to reduce its size.
Parameters:  a : array_like
n : int, optional
axis : int, optional


See also
Notes
The input array is expected to be packed the same way as the output of fft, as discussed in the fft documentation.
This is the inverse of fft: ifft(fft(a)) == a within numerical accuracy.
This is most efficient for n a power of two. This also stores a cache of working memory for different sizes of fft’s, so you could theoretically run into memory problems if you call this too many times with too many different n values.