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Multidimensional inverse fast Fourier transform

`X = ifftn(`

returns
the multidimensional
discrete inverse Fourier transform of an N-D array using a
fast Fourier transform algorithm. The N-D inverse transform is equivalent
to computing the 1-D inverse transform along each dimension of `Y`

)`Y`

.
The output `X`

is the same size as `Y`

.

`X = ifftn(`

truncates `Y`

,`sz`

)`Y`

or
pads `Y`

with trailing zeros before taking the inverse
transform according to the elements of the vector `sz`

.
Each element of `sz`

defines the length of the corresponding
transform dimension. For example, if `Y`

is a 5-by-5-by-5
array, then `X = ifftn(Y,[8 8 8])`

pads each dimension
with zeros, resulting in an 8-by-8-by-8 inverse transform `X`

.

The

`ifftn`

function tests whether the vectors in an array`Y`

are conjugate symmetric in all dimensions. A vector`v`

is conjugate symmetric when the*i*th element satisfies`v(i) = conj(v([1,end:-1:2]))`

. If the vectors in`Y`

are conjugate symmetric in all dimensions, then the inverse transform computation is faster and the output is real.