How can I solve this S-function problem?

Hy, I have a problem with my S-function. I got this error Could anybody help me pls Error: Error evaluating parameter '[t,x,u,flag,ni,n,p,q,fuzzy_m,Ts,x_0]' in 'Model_nou_fuzzyd_date3/S-Function Modelul dinamic Takagi-Sugeno al procesului condus'

Caused by: Undefined function or variable 'x'.

This is my code:

function [sys,x0,str,ts] = S_mod_fuz_procd(ni,n,p,q,fuzzy_m,Ts,x_0) % S-function for defining a dynamic Takagi-Sugeno fuzzy model of a discrete-time system % x' = Sum[(h_i(z))(A_i x + B_i u) % y = Sum[(h_i(z))(C_i x + D_i u)] % The dynamic fuzzy model is given in the variable fuzzy_m (FIS)

switch flag,

%%%%%%%%%%%%%%%%%%
% Initialization %
%%%%%%%%%%%%%%%%%%
case 0,
  [sys,x0,str,ts]=mdlInitializeSizes(ni,n,p,q,fuzzy_m,Ts,x_0);

%%%%%%%%%%
% Update %
%%%%%%%%%%
case 2,
  sys=mdlUpdate(t,x,u,ni,n,p,q,fuzzy_m,Ts);

%%%%%%%%%%%
% Outputs %
%%%%%%%%%%%
case 3,
  sys=mdlOutputs(t,x,u,ni,n,p,q,fuzzy_m,Ts);

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

%%%%%%%%%%%%%%%%%%%%
% Unexpected flags %
%%%%%%%%%%%%%%%%%%%%
otherwise
  error(['Unhandled flag = ',num2str(flag)]);

end % end csfunc

% %============================================================================= % mdlInitializeSizes % Return the sizes, initial conditions, and sample times for the S-function. %============================================================================= % function [sys,x0,str,ts]=mdlInitializeSizes(ni,n,p,q,fuzzy_m,Ts,x_0)

sizes = simsizes; sizes.NumContStates = 0; sizes.NumDiscStates = n; sizes.NumOutputs = q+n; % Additional outputs: the first q outputs correspond to system's outputs and the rest of n % outputs corespond to system's state variables: sizes.NumInputs = ni+p; sizes.DirFeedthrough = 1; sizes.NumSampleTimes = 1;

sys = simsizes(sizes); x0=x_0; str = []; ts = [Ts 0];

% end mdlInitializeSizes % %============================================================================= % mdlUpdate % Handle discrete state updates, sample time hits, and major time step % requirements. %============================================================================= % function sys=mdlUpdate(t,x,u,ni,n,p,q,fuzzy_m,Ts)

outfuz=evalfis([u' x'],fuzzy_m)';

sys = outfuz(1:n,1); ccc=isnan(sys); [mm1 mm2]=size(ccc); if ccc~=zeros(mm1,mm2), sys=zeros(mm1,mm2); end

% end mdlUpdate % %============================================================================= % mdlOutputs % Return the block outputs. %============================================================================= % function sys=mdlOutputs(t,x,u,ni,n,p,q,fuzzy_m,Ts)

outfuz=evalfis([u' x'],fuzzy_m)';

sys=zeros(q+n,1); % Initial value of output vector

ddd = outfuz(n+1:n+q,1); ccc=isnan(ddd); [mm1 mm2]=size(ddd); if ccc~=zeros(mm1,mm2), ddd=zeros(mm1,mm2); end

% The first q outputs correspond to system's outputs and the rest of n % outputs corespond to system's state variables:

sys(1:q,1)=ddd;

sys(q+1:q+n,1)=x;

% end mdlOutputs