basic operations, could someone help me do this?

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Gentrit Mehmeti 2019-11-11

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编辑： Gentrit Mehmeti 2019-11-11

Create two random matrices in Matlab, A (n x m) and B (m x n). a) Find the product ? = ? ∙ ?; b) Create a symmetric matrix D using C; c) Find the eigenvalues and eigenvectors of matrix D; d) Sort the eigenvalues and the eigenvectors according ascending/descending order of eigenvalues; e) Sort the eigenvalues and the eigenvectors according to a random order; f) Plot the eigenvalues and the accumulative eigenvalues; g) Plot the dot product matrix of eigenvectors as a 2D surface.

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darova 2019-11-11

What have you tried?

Gentrit Mehmeti 2019-11-11

编辑：Gentrit Mehmeti 2019-11-11

this, i got this as a school project for tomorrow midterm exam and I did this with the help of previous answer, if this what i've done is okay only the sort in random order and the plots are left, I would appreciate any help given

% creating two random matrices A and B.

A = rand(4,4);

B = rand(4,4);

% a) The product of two matrices A and B

C = A*B;

% b) Symmetric matrix D using C

D = C+C';

% c) Eigenvalues and eigenvectors of matrix D

[V,E] = eig(D);

% d) Sorting the eigenvalues and eigenvectors according ascend/descending

% order of eigenvalues

%there are multiple ways doing this, one of them is this:

% ascending order Eigenvalues

E_ascend = sort(E, 1, 'ascend');

E_ascend_result = sort(E_ascend, 2, 'ascend');

%descending order Eigenvalues

E_descend = sort(E, 1, 'descend');

E_descend_result = sort(E_descend, 2, 'descend');

%ascending order of eigenvectors

V_ascend = sort(V, 1, 'ascend');

V_ascend_result = sort(V_ascend, 2, 'ascend')

%descending order or eigenvectors

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Answer 1

aweller3 2019-11-11

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This is a partial answer. To create a random mXn matrix you can use A=rand(m,n) with m rows and n columns, with random values between 0 and 1. For some purposes I think rand might not be truly random but this is way beyond my level. If you need integers randi(m,n) should work. For the product just type C=A*B

For the eigenvalues and eigen vectors lookup the eig function here: https://www.mathworks.com/help/matlab/ref/eig.html

[V,L]=eig(D) will give eigenvectors of D stored in V and eigenvalues stored in L once you find the matrix D.

Information on plot can be found here:

https://www.mathworks.com/help/matlab/ref/plot.html