Mercurial > octave-dspies
view scripts/signal/ifftshift.m @ 19010:3fb030666878 draft default tip dspies
Added special-case logical-indexing function
* logical-index.h (New file) : Logical-indexing function. May be called on
octave_value types via call_bool_index
* nz-iterators.h : Add base-class nz_iterator for iterator types. Array has
template bool for whether to internally store row-col or compute on the fly
Add skip_ahead method which skips forward to the next nonzero after its
argument
Add flat_index for computing octave_idx_type index of current position (with
assertion failure in the case of overflow)
Move is_zero to separate file
* ov-base-diag.cc, ov-base-mat.cc, ov-base-sparse.cc, ov-perm.cc
(do_index_op): Add call to call_bool_index in logical-index.h
* Array.h : Move forward-declaration for array_iterator to separate header file
* dim-vector.cc (dim_max): Refers to idx-bounds.h (max_idx)
* array-iter-decl.h (New file): Header file for forward declaration of
array-iterator
* direction.h : Add constants fdirc and bdirc to avoid having to reconstruct
them
* dv-utils.h, dv-utils.cc (New files) :
Utility functions for querying and constructing dim-vectors
* idx-bounds.h (New file) :
Utility constants and functions for determining whether things will overflow
the maximum allowed bounds
* interp-idx.h (New function : to_flat_idx) : Converts row-col pair to linear
index of octave_idx_type
* is-zero.h (New file) : Function for determining whether an element is zero
* logical-index.tst : Add tests for correct return-value dimensions and large
sparse matrix behavior
author | David Spies <dnspies@gmail.com> |
---|---|
date | Fri, 25 Jul 2014 13:39:31 -0600 |
parents | d63878346099 |
children |
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## Copyright (C) 1997-2013 Vincent Cautaerts ## ## This file is part of Octave. ## ## Octave is free software; you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 3 of the License, or (at ## your option) any later version. ## ## Octave is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ## General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {} ifftshift (@var{x}) ## @deftypefnx {Function File} {} ifftshift (@var{x}, @var{dim}) ## Undo the action of the @code{fftshift} function. For even length ## @var{x}, @code{fftshift} is its own inverse, but odd lengths differ ## slightly. ## @end deftypefn ## Author: Vincent Cautaerts <vincent@comf5.comm.eng.osaka-u.ac.jp> ## Created: July 1997 ## Adapted-By: jwe ## Modified-By: Paul Kienzle, converted from fftshift ## Modified-By: David Bateman, add NDArray capability and option dim arg function retval = ifftshift (x, dim) retval = 0; if (nargin != 1 && nargin != 2) print_usage (); endif if (nargin == 2) if (! isscalar (dim)) error ("ifftshift: dimension must be an integer scalar"); endif nd = ndims (x); sz = size (x); sz2 = floor (sz(dim) / 2); idx = repmat ({':'}, nd, 1); idx{dim} = [sz2+1:sz(dim), 1:sz2]; retval = x(idx{:}); else if (isvector (x)) xl = length (x); xx = floor (xl/2); retval = x([xx+1:xl, 1:xx]); elseif (ismatrix (x)) nd = ndims (x); sz = size (x); sz2 = floor (sz ./ 2); idx = cell (); for i = 1:nd idx{i} = [sz2(i)+1:sz(i), 1:sz2(i)]; endfor retval = x(idx{:}); else error ("ifftshift: expecting vector or matrix argument"); endif endif endfunction %!test %! x = [0:7]; %! y = ifftshift (x); %! assert (y, [4 5 6 7 0 1 2 3]); %! assert (ifftshift (y), x); %!test %! x = [0:6]; %! y = ifftshift (x); %! assert (y, [3 4 5 6 0 1 2]); %! assert (ifftshift (y), [6 0 1 2 3 4 5]); %!test %! x = [0:7]'; %! y = ifftshift (x); %! assert (y, [4;5;6;7;0;1;2;3]); %! assert (ifftshift (y), x); %!test %! x = [0:6]'; %! y = ifftshift (x); %! assert (y, [3;4;5;6;0;1;2]); %! assert (ifftshift (y), [6;0;1;2;3;4;5]); %!test %! x = [0:3]; %! x = [x;2*x;3*x+1;4*x+1]; %! y = ifftshift (x); %! assert (y, [[7 10 1 4];[9 13 1 5];[2 3 0 1];[4 6 0 2]]); %! assert (ifftshift (y), x); %!test %! x = [0:3]; %! x = [x;2*x;3*x+1;4*x+1]; %! y = ifftshift (x,1); %! assert (y, [[1 4 7 10];[1 5 9 13];[0 1 2 3];[0 2 4 6]]); %! assert (ifftshift (y,1), x); %!test %! x = [0:3]; %! x = [x;2*x;3*x+1;4*x+1]; %! y = ifftshift (x,2); %! assert (y, [[2 3 0 1];[4 6 0 2];[7 10 1 4];[9 13 1 5]]); %! assert (ifftshift (y,2), x);