`(y)=fft2(x)`

Inputs | |

`x` |
A two dimensional array of real or complex numbers. |

Outputs | |

`y` |
A two dimensional array of complex numbers. |

The output of

`fft2`

is the Fast Fourier Transform of the input. Prior
to the computation of the transform, the input is
padded with sufficient number of rows and columns with zeros so that
both the row size and the column size of the array are powers of 2.
The FFT of a two-dimensional array is computed by two stages: (a) first a matrix is computed such that each of its columns is the FFT of the corresponding column of the (appropriated padded, if necessary) input, and then (b) a matrix is computed such that each of its rows is the FFT of the corresponding row of the matrix computed in the first step.