Calculating a matrix from other matrices

3 vues (au cours des 30 derniers jours)
Saleh Msaddi
Saleh Msaddi le 15 Fév 2021
Modifié(e) : Matt J le 15 Fév 2021
How can I write the following matrix?
M = [C*B;
C*A*B + C*B;
C*A^2*B + C*A*B + C*B;
.
.
.
C*A^(N-1)*B + C*A^(N-2)*B + ... + C*B];
A, B, and C are 2D arrays with size(A)=(n,n), size(B)=(n,p), and size(C)=(q,n). N is a positive integer.
  1 commentaire
Walter Roberson
Walter Roberson le 15 Fév 2021
I posted code for the 2D version of this a couple of years ago, where the values were being copied down the diagonals.
Unfortunately it has been far too long for me to recall the key words that would needed to find it within my other posts :(

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Réponses (1)

Matt J
Matt J le 15 Fév 2021
Q=eye(n);
Mcell=cell(n,1);
for i=1:N
Mcell{i}=C*Q*B;
Q=A*Q+Q;
end
M=cell2mat(Mcell);
  2 commentaires
Saleh Msaddi
Saleh Msaddi le 15 Fév 2021
Thanks @Matt J for your answer. However, I tried to execute the code and compre the results but they are not the same (only the first 2 rows are the same)
N = 4;
A = rand(4);
B = rand(4,1);
C = rand(1,4);
[n,p] = size(B);
R = [C*B;
C*A*B + C*B;
C*A^2*B + C*A*B + C*B;
C*A^3*B + C*A^2*B + C*A*B + C*B];
Q=eye(n);
Mcell=cell(n,1);
for i=1:N
Mcell{i}=C*Q*B;
Q=A*Q+Q;
end
M=cell2mat(Mcell);
R == M
Matt J
Matt J le 15 Fév 2021
Modifié(e) : Matt J le 15 Fév 2021
Sorry, it should be
N = 4;
A = rand(4);
B = rand(4,1);
C = rand(1,4);
[n,p] = size(B);
R = [C*B;
C*A*B + C*B;
C*A^2*B + C*A*B + C*B;
C*A^3*B + C*A^2*B + C*A*B + C*B];
[Q,Q0]=deal(eye(n));
Mcell=cell(n,1);
for i=1:N
Mcell{i}=C*Q*B;
Q=A*Q+Q0;
end
M=cell2mat(Mcell);
difference=norm(R-M)
difference = 1.8310e-15

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