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Create local repository for matrix toolboxes. Step #0 done.
author Antonio Pino Robles <data.script93@gmail.com>
date Wed, 06 May 2015 14:56:53 +0200
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8f23314345f4 Create local repository for matrix toolboxes. Step #0 done.
Antonio Pino Robles <data.script93@gmail.com>
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1 function [M,ind,n_swaps] = swapping(m)
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2 %SWAPPING Confluent permutation by swapping adjacent elements.
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3 % [ISWAP,IND,N_SWAPS] = SWAPPING(M) takes a vector M containing
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4 % the integers 1:k (some repeated if K < LENGTH(M))
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5 % and constructs a swapping scheme that produces
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6 % a confluent permutation, with elements ordered by ascending
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7 % average position. The confluent permutation is obtained by using
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8 % the LAPACK routine ZTREX to move m(ISWAP(i,2)) to m(ISWAP(i,1))
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9 % by swapping adjacent elements, for i = 1:SIZE(M,1).
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10 % The cell array vector IND defines the resulting block form:
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11 % IND{i} contains the indices of the i'th block in the permuted form.
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12 % N_SWAPS is the total number of swaps required.
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13
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14 mmax = max(m); M = []; ind = {}; h = zeros(1,mmax);
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15 g = zeros(1,mmax);
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16
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17 for i = 1:mmax
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18 p = find(m==i);
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19 h(i) = length(p);
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20 g(i) = sum(p)/h(i);
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21 end
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22
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23 [x,y] = sort(g);
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24 mdone = 1;
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25
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26 for i = y
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27 if any(m(mdone:mdone+h(i)-1) ~= i)
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28 f = find(m==i); g = mdone:mdone+h(i)-1;
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29 ff = f(f~=g); gg = g(f~=g);
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31 % Create vector v = mdone:f(end) with all elements of f deleted.
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32 v = mdone-1 + find(m(mdone:f(end)) ~= i);
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33
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34 % v = zeros(1,f(end)-g(1)+1);
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35 % v(f-g(1)+1) = 1; v = g(1)-1 + find(v==0);
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37 M(end+1:end+length(gg),:) = [gg' ff'];
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39 m(g(end)+1:f(end)) = m(v);
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40 m(g) = i*ones(1,h(i));
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41 ind = cat(2,ind,{mdone:mdone+h(i)-1}); mdone = mdone + h(i);
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42 else
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43 ind = cat(2,ind,{mdone:mdone+h(i)-1}); mdone = mdone + h(i);
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44 end
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45 end
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47 n_swaps = sum(abs(diff(M')));