If i have a given Matrix (k x k), how can i expand it to a (n x n) matrix?

I have to do a QR-decomposition of a Matrix A.

In my Code i have a matrix B (the dimensions are k x k) and i have work with a matrix C (the dimensions are n x n, while n >k)

The matrix C looks just like the identity matrix with the matrix B in the bottom right corner...

Can anyone help me how to write that?

(Sorry, neither my english nor my matlab skills are great :D )

[Rik]

Have a read here and here. It will greatly improve your chances of getting an answer.

Answer 1

[Doddy Kastanya]

It is not clear how the B and C matrices are related to A. However, if you just want to do QR decomposition, you might want to try "help qr" in MATLAB. It might have the information you need.