fft:

Syntax:	fft ( X )
	fft ( X , N )

Description:

	Fft utilizes the FFTPACK subroutine CFFTF to compute a
	discrete forward Fourier transform of the input.

	If fft is used with a second argument, N, then the matrix X is
	either padded with zeros, or truncated till it is of length N
	(if X is a vector), or has row dimension N (if it is a
	matrix).

	Subroutine CFFTF computes the forward complex discrete Fourier
	transform (the Fourier analysis). equivalently , CFFTF
	computes the Fourier coefficients of a complex periodic
	sequence.

	for j=1,...,n
	
           c(j)=the sum from k=1,...,n of
	
                 c(k)*exp(-i*(j-1)*(k-1)*2*pi/n)
	
                       where i=sqrt(-1)

	The argument X must be a matrix. If X is a row, or column
	matrix then a vector fft is performed. If X is a MxN matrix
	then the N columns of X are fft'ed.

See Also: ifft
