FFT

fft(a[, n, axis, stream])	One dimensional discrete Fourier Transform.
ifft(a[, n, axis, stream])	One dimensional inverse discrete Fourier Transform.
fft2(a[, s, axes, stream])	Two dimensional discrete Fourier Transform.
ifft2(a[, s, axes, stream])	Two dimensional inverse discrete Fourier Transform.
fftn(a[, s, axes, stream])	n-dimensional discrete Fourier Transform.
ifftn(a[, s, axes, stream])	n-dimensional inverse discrete Fourier Transform.
rfft(a[, n, axis, stream])	One dimensional discrete Fourier Transform on a real input.
irfft(a[, n, axis, stream])	The inverse of rfft().
rfft2(a[, s, axes, stream])	Two dimensional real discrete Fourier Transform.
irfft2(a[, s, axes, stream])	The inverse of rfft2().
rfftn(a[, s, axes, stream])	n-dimensional real discrete Fourier Transform.
irfftn(a[, s, axes, stream])	The inverse of rfftn().