Create a matrix using offset elements of a vector

Let say I have a vector v = [v1, v2, v3], I would like to create a non-square matrix putting the vector v as tridiagonal elements like this ,

matrix = [v1, v2, v3, 0, 0, 0,..., 0;

0 , v1,v2,v3, 0, 0 ,...,0;

0 , 0, v1,v2,v3,0,.....,0;]

I know there's a diag command but it's only for square matrix. What's the way of creating a non-square matrix?

Answer 1

[Kanika Gupta]

Try blktridiag:

A = blktridiag([1;2],[3;4],[5;6],4); 
full(A) 
ans = 
     1     5     0     0 
     2     6     0     0 
     3     1     5     0 
     4     2     6     0 
     0     3     1     5 
     0     4     2     6 
     0     0     3     1 
     0     0     4     2 

https://www.mathworks.com/matlabcentral/fileexchange/10603-block-tri-diagonal-matrices

Run help blktridiag for more info

[WeiShan Ng]

Thank you. This is exactly what I am looking for!