S-function error

Hi,Help please,when i try to use the follow s-function in a simulink blocket, i obtain this error:

Error in 'NARMA/S-Function' while executing MATLAB S-function 'NARMASYSTEM', flag = 3 (output), at time 0.0.
Too many output arguments.

This is the function code:

function [sys,x0,str,ts] = NARMASYSTEM(t,x,u,flag)
%M-file S-function for defining a discrete system.
% This S-function implements discrete equations
% Generate a discrete linear system:
a1=0.2;
a2=0.1;
g1=1;
g2=0.2;%=-0.2
b1=0.3;
b2=-0.6;

switch flag,
  case 0
    [sys,x0,str,ts] = mdlInitializeSizes(a1,a2,g1,g2,b1,b2); % Initialization

    case 2
     [sys,x0,str,ts] = mdlUpdates(t,x,u,a1,a2,g1,g2,b1,b2); % Update discrete states

    case 3
      [sys,x0,str,ts] = mdlOutputs(t,x,u,a1,a2,g1,g2,b1,b2); % Calculate outputs

    case {1, 4, 9} % Unused flags
      sys = [];

    otherwise
      error(['unhandled flag = ',num2str(flag)]); % Error handling
  end
  % End of dsfunc.

%==============================================================
% Initialization
%==============================================================

function [sys,x0,str,ts] = mdlInitializeSizes(a1,a2,g1,g2,b1,b2)

% Call simsizes for a sizes structure, fill it in, and convert it 
% to a sizes array.

sizes = simsizes;
sizes.NumContStates  = 0;
sizes.NumDiscStates  = 2;
sizes.NumOutputs     = 2;
sizes.NumInputs      = 2;
sizes.DirFeedthrough = 0; % Matrix D is non-empty.
sizes.NumSampleTimes = 1;
sys = simsizes(sizes); 
x0  = [0 1];   % Initialize the discrete states.
str = [];          % Set str to an empty matrix.
ts  = [1 0];       % sample time: [period, offset]
% End of mdlInitializeSizes.

%==============================================================
% Update the discrete states
%==============================================================
function sys = mdlUpdates(t,x,u,a1,a2,g1,g2,b1,b2)
sys(1) =a1*x(1)*cos(x(1))+a2*(x(1)^2)/(1+x(1)^2)+g1*x(2) ;
sys(2)=b1*sin(x(1))+b2*(x(1)^3)/(2+x(1)^2)+g2*u(1)+u(2);
% End of mdlUpdate.

%==============================================================
% Calculate outputs
%==============================================================
function sys = mdlOutputs(t,x,u,a1,a2,g1,g2,b1,b2)
sys=x;
% End of mdlOutputs.

Answer 1

[Kaustubha Govind]

Iman: I would recommend looking at some of Level-1 S-function demos. Type "sfundemos" at the MATLAB prompt and select MATLAB file S-functions -> Level-1 MATLAB S-functions. Please use these as a starting point and compare your S-function code with these to see if you can figure out what is going on.

You have been asking a slew of questions without any indication of having debugged/understood the issue yourself, so I'm trying to teach you to fish here. :)

Hint: Look at how mdlOutputs is called in the examples.

[iman]

Excuse me dear Kaustubha,actually i wrote many s-functions for nonlinear continues-time systems ,but

in my adaptive control project i force to simulate a nonlinear discrete-time system :-/

for this,i have confused :(

[Kaustubha Govind]

Iman: I see. I thought that you might be new to S-functions because the errors you are running into are basic syntax issues. I am surprised that they make a difference between continuous and discrete states systems - I would expect the three questions you have faced so far to cause similar issues if used inside continuous-time Level-1 MATLAB S-functions.

In any case, please feel free to ask in a comment if my answer didn't help you.

[iman]

Dear Kaustubha,

I really appreciate your response to me and I would like to thank you for your time and patience :).

I have received your comment and I thank you for your help so very much :) :).

Finally I found my errors and I corrected my code and I see that does not exist difference between continuous and discrete systems ;) ;) ;) ;).

In future, since in this semester I have a lot of projects related to MATLAB especially to simulink,I will communicate with you.

Best wishes

byeeeeeeeeee