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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 H = hadamard(n)
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2 %HADAMARD Hadamard matrix.
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3 % HADAMARD(N) is a Hadamard matrix of order N, that is,
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4 % a matrix H with elements 1 or -1 such that H*H' = N*EYE(N).
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5 % An N-by-N Hadamard matrix with N>2 exists only if REM(N,4) = 0.
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6 % This function handles only the cases where N, N/12 or N/20
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7 % is a power of 2.
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9 % Reference:
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10 % S.W. Golomb and L.D. Baumert, The search for Hadamard matrices,
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11 % Amer. Math. Monthly, 70 (1963) pp. 12-17.
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13 % History:
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14 % NJH (11/14/91), revised by CBM, 6/24/92,
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15 % comment lines revised by NJH, August 1993.
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16
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17 [f,e] = log2([n n/12 n/20]);
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18 k = find(f==1/2 & e>0);
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19 if isempty(k)
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20 error(['N, N/12 or N/20 must be a power of 2.']);
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21 end
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22 e = e(k)-1;
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23
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24 if k == 1 % N = 1 * 2^e;
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25 H = [1];
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27 elseif k == 2 % N = 12 * 2^e;
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28 H = [ones(1,12); ones(11,1) ...
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29 toeplitz([-1 -1 1 -1 -1 -1 1 1 1 -1 1],[-1 1 -1 1 1 1 -1 -1 -1 1 -1])];
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31 elseif k == 3 % N = 20 * 2^e;
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32 H = [ones(1,20); ones(19,1) ...
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33 hankel([-1 -1 1 1 -1 -1 -1 -1 1 -1 1 -1 1 1 1 1 -1 -1 1], ...
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34 [1 -1 -1 1 1 -1 -1 -1 -1 1 -1 1 -1 1 1 1 1 -1 -1])];
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35 end
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37 % Kronecker product construction.
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38 for i = 1:e
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39 H = [H H
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40 H -H];
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41 end