Make a larger matrix from smaller ones

what I am trying to do in matlab is making a matrix from 2 smaller ones in a specific order

consider we have 2 matrices 2*2 called A and B. where k1 and k2 are constants

k1 = 50 k2 = 100

A = [k1 -k1; -k1 k1] B = [k2 -k2; -k2 k2]

now i want it to look like this in a larger matrix

C = [k1 -k1 0; -k1 k1+k2 -k2;0 -k2 k2]

is this possiple to do in matlab? this is just an simple example but i genarelly works with much larger matrixes with the same order.

thanks in advance :-)

[James Tursa]

Can you give the pattern for the "much larger matrices"?

[Ahmad El-Kassem]

i can do that but the pattern is the same as the the above eksample. i was just thinking that if i can solve a simple problem in matlab then i also could solve a larger one.

this is an exsample that i had to write in matlab manually

[Stephen23]

Saying "the pattern is the same" does not clarify anything. This is the matrix from Forum.m in the comment above:

k3*c3^2+k1*c1^2        k3*(c3*s3)+k1*(c1*s1)  k1*(-c1^2)             k1*(-c1*s1)            k3*(-c3^2)                        k3*(-c3*s3)                       0            0
k3*(c3*s3)+k1*(c1*s1)  k3*s3^2+k1*s1^2        k1*(-c1*s1)            k1*(-s1^2)             k3*(-c3*s3)                       k3*(-s3^2)                        0            0
k1*(-c1^2)             k1*(-c1*s1)            k1*c1^2+k2*c2^2        k1*(c1*s1)+k2*(c2*s2)  k2*(-c2^2)                        k2*(-c2*s2)                       0            0
k1*(-c1*s1)            k1*(-s1^2)             k1*(c1*s1)+k2*(c2*s2)  k1*s1^2+k2*s2^2        k2*(-c2*s2)                       k2*(-s2^2)                        0            0
k3*(-c3^2)             k3*(-c3*s3)            k2*(-c2^2)             k2*(-c2*s2)            k4*c4^2+k3*c3^2+k2*c2^2           k4*(c4*s4)+k3*(c3*s3)+k2*(c2*s2)  k4*(-c4^2)   k4*(-c4*s4)
k3*(-c3*s3)            k3*(-s3^2)             k2*(-c2*s2)            k2*(-s2^2)             k4*(c4*s4)+k3*(c3*s3)+k2*(c2*s2)  k4*s4^2+k3*s3^2+k2*s2^2           k4*(-c4*s4)  k4*(-s4^2)
0                      0                      0                      0                      k4*(-c4^2)                        k4*(-c4*s4)                       k4*c4^2      k4*(c4*s4)
0                      0                      0                      0                      k4*(-c4*s4)                       k4*(-s4^2)                        k4*(c4*s4)   k4*c4^2

[David Goodmanson]

Hello Ahmad, Is your intent perhaps addition of translated matrices?

k1 = 50; k2 = 100;
A = [k1 -k1; -k1 k1];
B = [k2 -k2; -k2 k2];
C = zeros(3,3);
C(1:2,1:2) = A;
C(2:3,2:3) = C(2:3,2:3) + B

C =
    50   -50     0
   -50   150  -100
     0  -100   100

[Ahmad El-Kassem]

Yes i am trying to do an addition of translated matrices but just on a larger scale. I saw my teacher make a loop to solve this

ps. i Forgot that the Forum.m is a special case that is not interested in this topic. Sorry :-)

[David Goodmanson]

Hi Ahmad, If you are saying that this website is not interested in this kind of problem, then that is not true. The initial comments above were about understanding the nature of the problem, not with the problem itself. People get assistance on indexing problems similar to this all the time. The only consideration is that the person asking the question has defined the issue, made an effort to solve it, and usually has supplied some code that does not work yet.