求助：将s-function名称导入模块是出错

cxt212

我自己写了个最小二乘法辨识电机参数的程序，将s-function名称导入模块是出错，one or more output arguments not assigned，是真么原因，另外s-function中可以声明全局变量吗？下面是程序：
function [sys,x0,str,ts] = dsfunc(t,x,u,flag)
% An example M-file S-function for defining a discrete system.
% This S-function implements discrete equations in this form:
%      x(n+1) = Ax(n) + Bu(n)
%      y(n)   = Cx(n) + Du(n)
%
% Generate a discrete linear system:

global y1;
global out Qn Pn Kn Q1;
out=[0;0;0;0;0];
Qn=[0 0 0 0 0 ];
Pn=10^5*eye(5);


switch flag,
  case 0
    sys = mdlInitializeSizes(); % Initialization

  case 2
    sys = mdlUpdate(t,x,u); % Update discrete states

  case 3
    sys = mdlOutputs(t,x,u); % 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()

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

sizes = simsizes;
sizes.NumContStates  = 0;
sizes.NumDiscStates  = 9;
sizes.NumOutputs     = 5;
sizes.NumInputs      = 9;
sizes.DirFeedthrough = 1; % Matrix D is nonempty.
sizes.NumSampleTimes = 1;
sys = simsizes(sizes);
x0  = ones(9,1);   % Initialize the discrete states.
str = [];          % Set str to an empty matrix.
ts  = [0.01 0];       % sample time: [period, offset]
% End of mdlInitializeSizes.

%==============================================================
% Update the discrete states
%==============================================================
function sys = mdlUpdates(t,x,u)
y1=u(5)-u(3)*u(9);
Kn=Pn*Qn/(1+Qn'*Pn*Qn);


% End of mdlUpdate.

%==============================================================
% Calculate outputs
%==============================================================
function sys = mdlOutputs(t,x,u)
Q1=[u(3);u(6);u(1);u(8)+u(9)*u(7);u(9)*u(2)];
out=out+Kn(y1-Qn'*out);
Pn=Pn-(Pn*Qn*Qn'*Pn)/(1+Qn'*Pn*Qn);
Qn=[Qn' Q1]';
sys=out;
% End of mdlOutputs.