用S函数写的一段根据转子位置求反电势的代码，但是老是报错，盼高手点评一下

张子富

function [sys,x0,str,ts,simStateCompliance] = emf(t,x,u,flag)
switch flag,

  %%%%%%%%%%%%%%%%%%
  % Initialization %
  %%%%%%%%%%%%%%%%%%
  case 0,
    [sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes;

  case 3,
    sys=mdlOutputs(t,x,u);
  case 9,
    sys=mdlTerminate(t,x,u);
  case {1,2,4}
   sys=[];
  otherwise
    DAStudio.error('Simulink:blocks:unhandledFlag', num2str(flag));

end

function [sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes(t,x,u)

sizes = simsizes;

sizes.NumContStates  = 0;
sizes.NumDiscStates  = 0;
sizes.NumOutputs     = 3;
sizes.NumInputs      = 1;
sizes.DirFeedthrough = 0;
sizes.NumSampleTimes = 1;   % at least one sample time is needed

sys = simsizes(sizes);

%
% initialize the initial conditions
%
x0  = [];

%
% str is always an empty matrix
%
str = [];

%
% initialize the array of sample times
%
ts  = [-1 0];


%
function sys=mdlDerivatives(t,x,u)

sys = [];

% end mdlDerivatives

%
%=============================================================================
% mdlUpdate
% Handle discrete state updates, sample time hits, and major time step
% requirements.
%=============================================================================
%
function sys=mdlUpdate(t,x,u)

sys = [];

% end mdlUpdate

%
%=============================================================================
% mdlOutputs
% Return the block outputs.
%=============================================================================
%
function sys=mdlOutputs(t,x,u)

if(u>=0)&&(u<pi/3)
sys=[1 -1 -u*6/pi+1];
elseif(u>=pi/3)&&(u<2*pi/3)
sys=[1 u*6/pi-3 -1];
elseif(u>=2*pi/3)&&(u<pi)
sys=[-u*6/pi+5 1 -1];
elseif(u>=pi)&&(u<4*pi/3)
sys=[-1 1 u*6/pi-7];
elseif(u>=4*pi/3)&&(u<5*pi/3)
sys=[-1 -u*6/pi+9 1];
elseif(u>=5*pi/3)&&(u<2*pi)
sys=[u*6/pi-11 -1 1];
end
% end mdlOutputs

%
%=============================================================================
% mdlGetTimeOfNextVarHit
% Return the time of the next hit for this block.  Note that the result is
% absolute time.  Note that this function is only used when you specify a
% variable discrete-time sample time [-2 0] in the sample time array in
% mdlInitializeSizes.
%=============================================================================
%
%function sys=mdlGetTimeOfNextVarHit(t,x,u)

%sampleTime = 1;    %  Example, set the next hit to be one second later.
%sys = t + sampleTime;

% end mdlGetTimeOfNextVarHit

%
%=============================================================================
% mdlTerminate
% Perform any end of simulation tasks.
%==========================================================================
%===
function sys=mdlTerminate(t,x,u)
sys = [];


错误信息如下：
Output argument "sys" (and maybe others) not assigned during call to "D:\MATLAB\R2009a\toolbox\simulink\blocks\emf.m>mdlOutputs".
% end mdlTerminate

yjhou

s函数一直用的少，搞不明白，感觉很复杂。
就提示来看，好像是sys必须赋值吧。

张子富

回复 2# yjhou

我也是刚用的啊，还有好多不是很了解