hi,

I'm trying to create a diagonal matrix, with two minor diagonals and one major diagonal. I already created the two minor, but I don't know how to create the main one.

Code:

`%diagonalmatrix `

D = diag((-1)*k_i,-1) + diag(k_i+k_(i+1)) + diag((-1)*k_i, 1);

diag((-1)*k_i,-1) and diag((-1)*k_i, 1) already work.

How to change diag(k_i+k_(i+1)) ?

Must I create a new matrix with the addition already included for the major diagonal? How to?

Thanks!

I included the concept in the attachment.

## Best Answer