Mathc matrices/03r

Calculer et dessiner les vecteurs propres d'une matrice 2x2

Copy/Paste into the octave window

% Matrix 2x2 -------------

A = round(randn(2));    %% A matrix 2x2
A = A'*A                %% A symetric matrix

% Eigenvectors, Eigenvalues 
[Evectors,Evalues] = eigs(A);

color1 = 'r' ;  % red
color2 = 'k' ;  % black

% Plot Eigenvectors
figure(1)
plot([0 Evectors(1,1)],[0 Evectors(2,1)],color1)
hold on
plot([0 Evectors(1,2)],[0 Evectors(2,2)],color2)

legend({'v_1';'v_2'})

axis([-1 1 -1 1])
axis square
%%

Calculer et dessiner les vecteurs propres d'une matrice 3x3

Copy/Paste into the octave window

% Matrix 3x3 ---------------------

B = round(randn(3));      %% A matrix 3x3
B = B'*B                  %% A symetric matrix

% Eigenvectors, Eigenvalues 
[Evectors,Evalues] = eigs(B);

color1 = 'r' ;  % red
color2 = 'k';   % black
color3 = 'b' ;  % blue

% Plot Eigenvectors
figure(1), hold on

plot3([0 Evectors(1,1)],[0 Evectors(2,1)],[0 Evectors(3,1)],color1)
plot3([0 Evectors(1,2)],[0 Evectors(2,2)],[0 Evectors(3,2)],color2)
plot3([0 Evectors(1,3)],[0 Evectors(2,3)],[0 Evectors(3,3)],color3)

legend({'v_1';'v_2';'v_3'})

axis([-1 1 -1 1 -1 1])
axis square
rotate3d on
%%