Mercurial > hg > octave-nkf
changeset 13233:914c0b103a3d stable
fftshift.m: Better explain operation in docstring (Bug #33581).
* fftshift.m: Improve docstring. Validate dimension input is truly a positive integer.
author | Rik <octave@nomad.inbox5.com> |
---|---|
date | Mon, 26 Sep 2011 11:43:20 -0700 |
parents | 9b98affe52b9 |
children | 00c5d8d3ee00 |
files | scripts/signal/fftshift.m |
diffstat | 1 files changed, 8 insertions(+), 7 deletions(-) [+] |
line wrap: on
line diff
--- a/scripts/signal/fftshift.m +++ b/scripts/signal/fftshift.m @@ -24,13 +24,15 @@ ## center of the vector or matrix. ## ## If @var{x} is a vector of @math{N} elements corresponding to @math{N} -## time samples spaced of @math{Dt} each, then @code{fftshift (fft -## (@var{x}))} corresponds to frequencies +## time samples spaced by @math{dt}, then +## @code{fftshift (fft (@var{x}))} corresponds to frequencies ## ## @example -## f = ((1:N) - ceil(N/2)) / N / Dt +## f = [ -(ceil((N-1)/2):-1:1)*df 0 (1:floor((N-1)/2))*df ] ## @end example ## +## where @math{df} = 1 / @math{dt}. +## ## If @var{x} is a matrix, the same holds for rows and columns. If ## @var{x} is an array, then the same holds along each dimension. ## @@ -44,15 +46,13 @@ function retval = fftshift (x, dim) - retval = 0; - if (nargin != 1 && nargin != 2) print_usage (); endif if (nargin == 2) - if (!isscalar (dim)) - error ("fftshift: dimension must be an integer scalar"); + if (! (isscalar (dim) && dim > 0 && dim == fix (dim))) + error ("fftshift: dimension DIM must be a positive integer"); endif nd = ndims (x); sz = size (x); @@ -84,6 +84,7 @@ endfunction + %!test %! x = [0:7]; %! y = fftshift (x);