Creating Matrix provided elements
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Karthik Nagaraj
am 22 Jul. 2021
Kommentiert: Karthik Nagaraj
am 24 Jul. 2021
From a Hermititan (complex skew symmetric) matrix of order N (Asssume N=15) a column vector is created such that all the diagonal elements are placed first and then the ordered pair of real and imaginary parts of upper triangle matrix are placed next. Since it is hermitian matrix the upper and lower triangle elements have same set of real and imaginary elements.
For example for N=15x15 matrix the vector looks like this
[D1, D2, D3,...........,D15, R11, I11,R12, I12,.... ,R15, I15] in total 225 elements column vector.
How to construct back the matrix given this vector?
4 Kommentare
Jan
am 23 Jul. 2021
What is R1_2 compared to L1_2? Should it be L2_1? If it is a hermitian matrix, why are the L elements stored?
Please explain exactly, what the inputs are. Use a 4x4 matrix to avoid the need to use unclear abbreviations.
Akzeptierte Antwort
Jan
am 24 Jul. 2021
Bearbeitet: Jan
am 24 Jul. 2021
A = rand(4) + 1i * rand(4);
A = A + A'; % Hermitian
% Convert to vector:
D = diag(A).';
L = triu(A, 1);
Lf = L(L ~= 0).';
Lv = [real(Lf); imag(Lf)];
VU = [D, Lv(:).'];
% And backwards:
n = sqrt(numel(VU));
L = triu(ones(n), 1);
L(L==1) = VU(n+1:2:n*n) + 1i * VU(n+2:2:n*n);
% Or: L(L==1) = [1, 1i] * reshape(VU(n+1:n*n), 2, [])
B = diag(VU(1:n)) + L + L';
isequal(A, B)
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Operating on Diagonal Matrices finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!