--- /dev/null
+## Copyright (C) 2004 Josep Mones i Teixidor
+##
+## This program 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 2 of the License, or
+## (at your option) any later version.
+##
+## This program 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 this program; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{vals}] = } qtgetblk (@var{I},@var{S},@var{dim})
+## @deftypefnx {Function File} {[@var{vals},@var{idx}] = } qtgetblk (@var{I},@var{S},@var{dim})
+## @deftypefnx {Function File} {[@var{vals},@var{r},@var{c}] = } qtgetblk (@var{I},@var{S},@var{dim})
+## Obtain block values from a quadtree decomposition.
+##
+## [vals]=qtgetblk(I,S,dim) returns a dim-by-dim-by-k array in
+## @var{vals} which contains the dim-by-dim blocks in the quadtree
+## decomposition (@var{S}, which is returned by qtdecomp) of @var{I}. If
+## there are no blocks, an empty matrix is returned.
+##
+## [vals,idx]=qtgetblk(I,S,dim) returns @var{vals} as described above.
+## In addition, it returns @var{idx}, a vector which contains the linear
+## indices of the upper left corner of each block returned (the same
+## result as find(full(S)==dim)).
+##
+## [vals,r,c]=qtgetblk(I,S,dim) returns @var{vals} as described, and two
+## vectors, @var{r} and @var{c}, which contain the row and column
+## coordinates of the blocks returned.
+##
+## @seealso{qtdecomp, qtsetblk}
+## @end deftypefn
+
+## Author: Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function [varargout] = qtgetblk(I, S, dim)
+ if (nargin!=3)
+ usage("[vals,r,c]=qtgetblk(I,S,dim), [vals,idx]=qtgetblk(I,S,dim)");
+ endif
+ if (nargout>3)
+ usage("[vals,r,c]=qtgetblk(I,S,dim), [vals,idx]=qtgetblk(I,S,dim)");
+ endif
+
+ ## get blocks
+ [i,j,v]=find(S);
+
+ ## filter the ones which match dim
+ idx=find(v==dim);
+
+ if(length(idx)==0)
+ for i=1:nargout
+ varargout{i}=[];
+ endfor
+ else
+ r=i(idx);
+ c=j(idx);
+
+ ## copy to a dim-by-dim-by-k array
+ vals=zeros(dim,dim,length(idx));
+ for i=1:length(idx)
+ vals(:,:,i)=I(r(i):r(i)+dim-1,c(i):c(i)+dim-1);
+ endfor
+
+ varargout{1}=vals;
+
+ if(nargout==3)
+ varargout{2}=r;
+ varargout{3}=c;
+ elseif(nargout==2)
+ varargout{2}=(c-1)*rows(I)+r;
+ endif
+ endif
+endfunction
+
+
+%!demo
+%! [vals,r,c]=qtgetblk(eye(4),qtdecomp(eye(4)),2)
+%! % Returns 2 blocks, at [1,3] and [3,1] (2*2 zeros blocks)
+
+%!shared A,S
+%! A=[ 1, 4, 2, 5,54,55,61,62;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 3, 6, 3, 1,58,53,67,65;
+%! 23,42,42,42,99,99,99,99;
+%! 27,42,42,42,99,99,99,99;
+%! 23,22,26,25,99,99,99,99;
+%! 22,22,24,22,99,99,99,99];
+%! S=qtdecomp(A,10);
+
+%!test
+%! [va]=qtgetblk(A,S,8);
+%! [vb,r,c]=qtgetblk(A,S,8);
+%! [vc,i]=qtgetblk(A,S,8);
+%! assert(va, vb);
+%! assert(va, vc);
+%! assert(i,[]);
+%! assert(r,[]);
+%! assert(c,[]);
+%! R=[];
+%! assert(va,R);
+
+
+%!test
+%! [va]=qtgetblk(A,S,4);
+%! [vb,r,c]=qtgetblk(A,S,4);
+%! [vc,i]=qtgetblk(A,S,4);
+%! assert(va, vb);
+%! assert(va, vc);
+%! assert(i, find(full(S)==4));
+%! assert(r,[1;5]);
+%! assert(c,[1;5]);
+%! R=zeros(4,4,2);
+%! R(:,:,1)=A(1:4,1:4);
+%! R(:,:,2)=A(5:8,5:8);
+%! assert(va,R);
+
+%!test
+%! [va]=qtgetblk(A,S,2);
+%! [vb,r,c]=qtgetblk(A,S,2);
+%! [vc,i]=qtgetblk(A,S,2);
+%! assert(va, vb);
+%! assert(va, vc);
+%! assert(i, find(full(S)==2));
+%! assert(r,[7;5;7;1;3;1;3]);
+%! assert(c,[1;3;3;5;5;7;7]);
+%! R=zeros(2,2,7);
+%! R(:,:,1)=A(7:8,1:2);
+%! R(:,:,2)=A(5:6,3:4);
+%! R(:,:,3)=A(7:8,3:4);
+%! R(:,:,4)=A(1:2,5:6);
+%! R(:,:,5)=A(3:4,5:6);
+%! R(:,:,6)=A(1:2,7:8);
+%! R(:,:,7)=A(3:4,7:8);
+%! assert(va,R);
+
+%
+% $Log$
+% Revision 1.4 2007/03/23 16:14:37 adb014
+% Update the FSF address
+%
+% Revision 1.3 2007/01/04 23:50:47 hauberg
+% Put seealso before end deftypefn
+%
+% Revision 1.2 2007/01/04 23:41:47 hauberg
+% Minor changes in help text
+%
+% Revision 1.1 2006/08/20 12:59:35 hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.3 2006/01/02 20:53:42 pkienzle
+% Reduce number of shared variables in tests
+%
+% Revision 1.2 2004/08/11 19:52:41 jmones
+% qtsetblk added
+%
+%
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