initial commit

+utils/pshift.m

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+% AOUT = pshift(AIN, CTRPOS)
+%
+% Shift array AIN periodically so that CTRPOS is placed at (1,1). 
+%
+
+%*-----------------------------------------------------------------------*
+%|                                                                       |
+%|  Except where otherwise noted, this work is licensed under a          |
+%|  Creative Commons Attribution-NonCommercial-ShareAlike 4.0            |
+%|  International (CC BY-NC-SA 4.0) license.                             |
+%|                                                                       |
+%|  Copyright (c) 2017 by Paul Scherrer Institute (http://www.psi.ch)    |
+%|                                                                       |
+%|       Author: CXS group, PSI                                          |
+%*-----------------------------------------------------------------------*
+% You may use this code with the following provisions:
+%
+% If the code is fully or partially redistributed, or rewritten in another
+%   computing language this notice should be included in the redistribution.
+%
+% If this code, or subfunctions or parts of it, is used for research in a 
+%   publication or if it is fully or partially rewritten for another 
+%   computing language the authors and institution should be acknowledged 
+%   in written form in the publication: “Data processing was carried out 
+%   using the “cSAXS matlab package” developed by the CXS group,
+%   Paul Scherrer Institut, Switzerland.” 
+%   Variations on the latter text can be incorporated upon discussion with 
+%   the CXS group if needed to more specifically reflect the use of the package 
+%   for the published work.
+%
+% A publication that focuses on describing features, or parameters, that
+%    are already existing in the code should be first discussed with the
+%    authors.
+%   
+% This code and subroutines are part of a continuous development, they 
+%    are provided “as they are” without guarantees or liability on part
+%    of PSI or the authors. It is the user responsibility to ensure its 
+%    proper use and the correctness of the results.
+
+function aout = pshift(ain, ctrpos, varargin)
+
+sz = size(ain);
+
+if length(sz) ~= 2
+    error('Unsupported array size');
+end
+
+ain_is_logical = islogical(ain);
+if ain_is_logical
+    ain = double(ain);
+end
+
+aout = zeros(sz,class(ain));
+ctr = mod(reshape(ctrpos, [1 2]) - 1, sz);
+
+ctr_int = round(ctr);
+ctr_dec = ctr - ctr_int;
+
+if nargin > 2
+    precision = varargin{1};
+else
+    precision = 1e-2;
+end
+
+use_dec = true;
+if max(max(abs(ctr_dec))) < precision
+    use_dec = false;
+end
+
+c2 = sz - ctr_int;
+
+
+% First the integral shift
+aout(1:c2(1),1:c2(2)) = ain(ctr_int(1)+1:end,ctr_int(2)+1:end);
+aout(1:c2(1),c2(2)+1:end) = ain(ctr_int(1)+1:end,1:ctr_int(2));
+aout(c2(1)+1:end,1:c2(2)) = ain(1:ctr_int(1),ctr_int(2)+1:end);
+aout(c2(1)+1:end,c2(2)+1:end) = ain(1:ctr_int(1),1:ctr_int(2));
+
+if use_dec
+    faout = fftn(aout);
+    [q1,q2] = ndgrid(-ceil(sz(1)/2):floor(sz(1)/2 - 1),-ceil(sz(2)/2):floor(sz(2)/2 - 1));
+    q1 = fftshift(q1);
+    q2 = fftshift(q2);
+    aout = ifftn( exp(2i * pi * (q2 * ctr_dec(2) / sz(2) + q1 * ctr_dec(1) / sz(1))) .* faout);
+end
+    
+if ain_is_logical
+    aout = logical(aout);
+end