I am working with Octave in the control package, and I want to take an array of transfer functions (initialized as follows) and just extract the diagonal elements of the matrix. Whenever I try to do this, I run into the following error. I have tried lots of workarounds (converting it to a state space diagram, storing the elements in a cell, etc.), but I either run into a similar error or I end up with an object that can no longer interact with other matrices of transfer functions. There are some unimplemented functions (like ss2ss) in the documentation that I think would be useful but are unavailable.
How can I work around this?
The code initializing the type of object I'm working with:
s = tf('s');
m = inv(s*e - mat); // e and mat are just square matrices of numbers
The code I am using to try to extract the diagonal components:
function D = getD(W) // W is of the similar type as above
n = size(W,1);
Dtemp = tf(eye(n));
for i = 1:n
Dtemp(i,i) = W(i,i);
end
D = Dtemp;
end
Errors that I keep getting:
error: lti: subsasgn: invalid subscripted assignment type '()'. you must select an LTI key first, i.e. sys.keyname(...) = ...
Note that when I initialized Dtemp as cell (n,n), I get this type:
{
[1,1] =
<class tf>
[2,1] =
<class tf>
etc.
Instead of this type: (which is what I want it to interact with)
{
[1,1] =
<class tf>
}
Even though they are both nxn in size. I am hoping to be able to convert the former into the latter, so I can interact with other objects of the latter type.
diag? – Cranage