X = diag(v,k) X = diag(v) v = diag(X,k) v = diag(X)
X = diag(v,k) when v is
a vector of n components, returns a square matrix X of
order n+abs(k), with the elements of v on
the kth diagonal. k = 0 represents
the main diagonal, k > 0 above the main diagonal,
and k < 0 below the main diagonal.
X = diag(v) puts v on
the main diagonal, same as above with k=0.
v = diag(X,k) for matrix X,
returns a column vector v formed from the elements
of the kth diagonal of X.
v = diag(X) returns the
main diagonal of X, same as above with k
= 0 .