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diag(1) Scilab Function diag(1)
NAME
diag - diagonal including or extracting
CALLING SEQUENCE
[y]=diag(vm, [k])
PARAMETERS
vm : vector or matrix
k : integer (default value 0)
y : vector or matrix
DESCRIPTION
for vm a (row or column) n-vector diag(vm) returns a diagonal matrix with
entries of vm along the main diagonal.
diag(vm,k) is a (n+abs(k))x(n+abs(k)) matrix with the entries of vm along
the kth diagonal. k=0 is the main diagonal k>0 is for upper diagonals and
k<0 for lower diagonals.
For a matrix vm, diag(vm,k) is the column vector made of entries of the kth
diagonal of vm. diag(vm) is the main diagonal of vm. diag(diag(x)) is a
diagonal matrix.
To construct a diagonal linear system, use sysdiag.
Note that eye(A).*A returns a diagonal matrix made with the diagonal
entries of A. This is valid for any matrix (constant, polynomial, rational,
state-space linear system,...).
For example
diag(-m:m) + diag(ones(2*m,1),1) +diag(ones(2*m,1),-1)
gives a tri-diagonal matrix of order 2*m+1
EXAMPLE
diag([1,2])
A=[1,2;3,4];
diag(A)
diag(A,1)
SEE ALSO
sysdiag
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