% -*- texinfo -*-
% @deftypefn {Function File} {} fftshift (@var{v})
% @deftypefnx {Function File} {} fftshift (@var{v}, @var{dim})
% Perform a shift of the vector @var{v}, for use with the @code{fft}
% and @code{ifft} functions, in order the move the frequency 0 to the
% center of the vector or matrix.
%
% If @var{v} is a vector of @math{N} elements corresponding to @math{N}
% time samples spaced of @math{Dt} each, then @code{fftshift (fft
% (@var{v}))} corresponds to frequencies
%
% @example
% f = ((1:N) - ceil(N/2)) / N / Dt
% @end example
%
% If @var{v} is a matrix, the same holds for rows and columns. If
% @var{v} is an array, then the same holds along each dimension.
%
% The optional @var{dim} argument can be used to limit the dimension
% along which the permutation occurs.
% @end deftypefn