Dimensions of matrices being concatenated are not consistent

t = 0:5640;                     % time taken for the system to run is from 0 to 5640s
i = 83*pi/180;                  % inclination angle in rad
w0 = 0.0011;                    % angular velocity in rad/s

a1 = sin(i)*cos(w0*t);
a2 = -cos(i);
a3 = 2*sin(i)*sin(w0*t);

A = [0 -a3 a2; a3 0 -a1; -a2 a1 0];

This is my coding and I would like to create a matrix A. It shows the error Error using vertcat: Dimensions of matrices being concatenated are not consistent when I computed it. I know the reason why, but how can I compute a matrix A with varying number of a1 and a3 while a2 is a constant?

[Peng Li]

I don’t really know the reason why you did this. But would an extension of a2 to size(t) fit your need? a2 = -cos(i) * ones(size(t));

[Linee Teh]

Thank you for your help and I successfully get a1, a2 and a3 with the same dimensions. However, my problem still haven't solve.

My full question is like below:

t = 0:5640;                     % time taken for the system to run is from 0 to 5640s
i = 83*pi/180;                  % inclination angle in rad
w0 = 0.0011;                    % angular velocity in rad/s

a1 = sin(i)*cos(w0*t);
a2 = -cos(i)*ones(size(t));
a3 = 2*sin(i)*sin(w0*t);

A = [1 0 0 0 a3 a2; 0 1 0 -a3 0 a1; 0 0 1 a2 -a1 0;...
    -1 0 0 0 0 0; 0 -1 0 0 0 0; 0 0 -1 0 0 0;...
    zeros(3) zeros(3)];

"Error using vertcat: Dimensions of matrices being concatenated are not consistent" still poping out with this code. I actually want to get A matrix with dimension 9 x 6 and also if possible, get matrix A for t = 0s, t=1s... t=5640s separately.

I hope my question is clear.

Answer 1

[Ameer Hamza]

In MATLAB, rows of a matrix cannot have different number of elements. For that, you will need to use a cell array

t = 0:5640;                     % time taken for the system to run is from 0 to 5640s
i = 83*pi/180;                  % inclination angle in rad
w0 = 0.0011;                    % angular velocity in rad/s
a1 = sin(i)*cos(w0*t);
a2 = -cos(i);
a3 = 2*sin(i)*sin(w0*t);
A = {[0 -a3 a2]; [a3 0 -a1]; [-a2 a1 0]};

[Linee Teh]

Hey, thank you for giving me advise. However, my question haven't solve.

t = 0:5640;                     % time taken for the system to run is from 0 to 5640s
i = 83*pi/180;                  % inclination angle in rad
w0 = 0.0011;                    % angular velocity in rad/s
a1 = sin(i)*cos(w0*t);
a2 = -cos(i)*ones(size(t));
a3 = 2*sin(i)*sin(w0*t);
A = [1 0 0 0 a3 a2; 0 1 0 -a3 0 a1; 0 0 1 a2 -a1 0;...
    -1 0 0 0 0 0; 0 -1 0 0 0 0; 0 0 -1 0 0 0;...
    zeros(3) zeros(3)];

"Error using vertcat: Dimensions of matrices being concatenated are not consistent" still poping out with this code. I actually want to get A matrix with dimension 9 x 6 and also if possible, get matrix A for t = 0s, t=1s... t=5640s separately to perform for different time frame. May I know what can I do to improve my coding to in order for me to get what I want?

I hope my question is clear.

[Ameer Hamza]

Ok It is clear now. Try this

t = 0:5640;                     % time taken for the system to run is from 0 to 5640s
i = 83*pi/180;                  % inclination angle in rad
w0 = 0.0011;                    % angular velocity in rad/s
a1 = sin(i)*cos(w0*t);
a2 = -cos(i)*ones(size(t));
a3 = 2*sin(i)*sin(w0*t);

ONE = ones(1,1,numel(a1));
ZERO = zeros(1,1,numel(a1));
a1 = reshape(a1, 1,1,[]);
a2 = reshape(a2, 1,1,[]);
a3 = reshape(a3, 1,1,[]);
A = [ONE    ZERO    ZERO    ZERO    a3      a2; 
     ZERO   ONE     ZERO    -a3     ZERO    a1; 
     ZERO   ZERO    ONE     a2      -a1     ZERO;
     -ONE   ZERO    ZERO    ZERO    ZERO    ZERO; 
     ZERO   -ONE    ZERO    ZERO    ZERO    ZERO; 
     ZERO   ZERO    -ONE    ZERO    ZERO    ZERO;
     zeros(3,3,numel(a1))   zeros(3,3,numel(a1))];

The matrix A is 9x6x5641. You can access value like this

A(:,:,1) % <-- t = 0
A(:,:,2) % <-- t = 1
A(:,:,3) % <-- t = 2
..
..
A(:,:,5641) % <-- t = 5640

[Linee Teh]

Really thank you for your help!!