How to create variable system in S-Function using feedback data from simulink or workspace)

Hello

Here,continues steady-space system is defined in S-Function block in simulink:

if true

   function [sys,x0,str,ts] = mycsfunc(t,x,u,flag)
%      x' = Ax + Bu
%      y  = Cx + Du
%
% Generate a continuous linear system:
A=[-1   -10
    1    0];
B=[ 1   -20
    0   -2];
C=[ 9    2
    1   -5];
D=[-14   0
    1    3];
%
% Dispatch the flag.
%
switch flag,
{1,3,9}
...
..
.
% 
End of mycsfunc.
%==============================================================
% mdlInitializeSizes
% Return the sizes, initial conditions, and sample times for the 
% S-function.
%==============================================================
%
function [sys,x0,str,ts] = mdlInitializeSizes(A,B,C,D)
%
% Call simsizes for a sizes structure, fill it in and convert it 
% to a sizes array.
%
sizes = simsizes;
sizes.NumContStates  = 2;
sizes.NumDiscStates  = 0;
sizes.NumOutputs     = 2;
sizes.NumInputs      = 2;
sizes.DirFeedthrough = 1;     % Matrix D is nonempty. 
sizes.NumSampleTimes = 1;
sys = simsizes(sizes);
...
..
.
End of mdlOutputs.

end

In simulink I have a variable prameters that can effect my system parameters. K is a parameter in simulink or workspace that can change continuously.How can I define this parameter to my s-function to get K , P data from simulink or workspace to create variable system like below in S-Function:(How to create variable parameter dependent system in S-Function as below)

if true
A=[-1  -P
  1    0];
B=[ 1   -20
  0   -2];
C=[ 9    2
  1   -5];
D=[-K   0
  1   3];
end

Thanks

Answer 1

[Kaustubha Govind]

You can simply add additional parameters to the main function as follows:

function [sys,x0,str,ts] = mycsfunc(t,x,u,flag,P,K)

and use these within the function and/or pass them onto to mdlInitializeSizes, mdlOutputs, etc.

On the S-function block, enter values for P and K (in that order) in the "S-function parameter" edit-box. These values can be constant numbers or mask/workspace variables, just like for other block parameters.

Also, note that you are using Level-1 S-functions which have been deprecated for several years and have a lot of limitations. I would recommend that you convert to Level-2 S-functions if possible.