# ifft2

2-D inverse fast Fourier transform

## Description

`X = ifft2(`

returns
the two-dimensional
discrete inverse Fourier transform of a matrix using a fast
Fourier transform algorithm. If `Y`

)`Y`

is a multidimensional
array, then `ifft2`

takes the 2-D inverse transform
of each dimension higher than 2. The output `X`

is
the same size as `Y`

.

## Examples

## Input Arguments

## More About

## Algorithms

The

`ifft2`

function tests whether the matrix`Y`

is conjugate symmetric. If`Y`

is conjugate symmetric, then the inverse transform computation is faster and the output is real.A function $$g(a,b)$$ is conjugate symmetric if $$g(a,b)={g}^{*}(-a,-b)$$. However, the fast Fourier transform of a 2-D time-domain signal has one half of its spectrum in positive frequencies and the other half in negative frequencies, with the first row and column reserved for the zero frequencies. For this reason, a matrix

`Y`

is conjugate symmetric when all of these conditions are true:`Y(1,2:end)`

is conjugate symmetric, or`Y(1,2:end) = conj(Y(1,end:-1:2))`

`Y(2:end,1)`

is conjugate symmetric, or`Y(2:end,1) = conj(Y(end:-1:2,1))`

`Y(2:end,2:end)`

is conjugate centrosymmetric, or`Y(2:end,2:end) = conj(Y(end:-1:2,end:-1:2))`

## Extended Capabilities

## Version History

**Introduced before R2006a**