Creating a Sparse Matrix

I have a big matrix B and I get it by concatenating the small matrices.

 B = [A1 M1 M2 Z1
     M1' M2' Z2 A2];    
 

But when I store this matrix, its size is very big and it takes up a lot of memory. I want to convert it to sparse matrix. The matrices Z1 and Z2 have all zero elements and, M1 and M2 also have a lot of zeros.

[Alex Mcaulley]

What is the question? you can use sparse function to convert your full matrix in sparse matrix

https://es.mathworks.com/help/matlab/ref/sparse.html

[Ahmad Hasnain]

Should I convert the small matrices to sparse and then add them to the big matrix or Can I assemble B in such a way that it ends up being a sparse matrix?

B = [A1 M1 M2 Z1
     M1' M2' Z2 A2];    

Because with this code I can't get a sparse matrix. Is there another way to assemble this matrix?

[Alex Mcaulley]

yes, you should convert your small matrix to sparse and then combine them to obtain the sparse big matrix to avoid problems with memory

[Jos (10584)]

What do you want to do with B? In other words, do you really need to create it?

[Ahmad Hasnain]

I use B in a quadratic equation. I need to multiply it with some vectors.