Effacer les filtres
Effacer les filtres

Preallocating matrix with a numeric trend

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Brian
Brian le 11 Jan 2016
Commenté : Brian le 11 Jan 2016
Hello all,
I manually wrote out the following matrix, IMiteration (since I didn't know how to code for it):
%%Define I1, I2 selection matrix (since not all combinations with higher
% keV at base is meaningful)
Mx1 = [40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 ...
45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 ...
50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 ...
55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 ...
60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 ...
65 65 65 65 65 65 65 65 65 65 65 65 65 65 65 ...
70 70 70 70 70 70 70 70 70 70 70 70 70 70]';
Mx2 = [45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 ...
75 80 85 90 95 100 105 110 115 120 125 130 135 140]';
IMiteration = [Mx1 Mx2];
Now, instead of having a step size of 5 in Mx2, I would like the step size to be 2 instead. So for example, the first 51 rows of the final product will have 40 in column 1, and 42:2:140 in column 2. The next 50 will have 42 in column 2, and 44:2:140 in column 2, and so on. Is there a smarter way to generate this matrix? Thanks.

Réponse acceptée

Stephen23
Stephen23 le 11 Jan 2016
Modifié(e) : Stephen23 le 11 Jan 2016
Here is a reasonably efficient solution:
U = 40:5:70; % values of Mx1
V = 45:5:140; % values of Mx2
M = numel(U);
N = numel(V);
Mx1 = repmat(U,N,1);
Mx1([1==triu(ones(M),1);false(N-M,M)]) = NaN;
Mx1 = Mx1(isfinite(Mx1));
Mx2 = hankel(V(1:M),[V(M:end),nan(1,M-1)]).';
Mx2 = Mx2(isfinite(Mx2));
  1 commentaire
Brian
Brian le 11 Jan 2016
Thank you! This is indeed efficient. :)

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