Is there anybody to help me fix the error and convert mxArray to double?

I am trying to implement the m-file into Matlab Function in Simulink. It needs to run some code conversion. Since "care()" function is not in the main library of this code converter, I have added coder.extrinsic('care'). Now when I run the Simulink it shows me the error as in the attached figure.

coder.extrinsic('care')

[~,~,G0] = care(hA, hB2, eye(4), eye(1), zeros(4,1), E);

KK=G0;

bA=hA-hB2*KK;

Now in my case bA(4x4 matrix), hB2(4x1 double), KK(1x4 mxArray). In fact after multiplication bA*hB2 should return 4x4 matrix. The problem is that KK should be double in order to work. How can I fix this issue of converting mxArray to double?

The code runs ok on m-file, but when I try to implement it on Simulink, it doesn't. I plan later to convert it to C++ code.

Answer 1

[James Tursa]

What happens if you add this prior to the "care" call:

G0 = zeros(1,4);

[Drill Be]

Thank you, it works. But now I faced another similar issue with mxArray when I want to multiply two state space systems. For instance G12*KK, it shows the same error mxArray. Both are State-space model with 3 outputs, 1 inputs, and 4 states.

[Prateek Tiwari]

@James

What if I do not know the size of varibale (G0) before hand?.