%% Create Diagonal Matrices
% Create a 1-by-5 vector.

v = [2 1 -1 -2 -5];

%
% Use diag to create a matrix with the elements of v on the main diagonal.

D = diag(v)

%
% Create a matrix with the elements of v on the first super diagonal (k=1).

D1 = diag(v,1)

% The result is a 6-by-6 matrix. When you specify a vector of length n as an input, diag returns a square matrix of size n+abs(k).
% Copyright 2012 The MathWorks, Inc.