运行S函数出现 flag=2 call must be a real vector of length 0错误

ezekyal

运行下面这个S函数，出现这种错误：
Discrete state(s) returned by S-function 'dtc' in 'untitled1/S-Function' during flag=2 call must be a real vector of length 0
以前见过是在FLAG=3的时候出现，这种情况到没遇到过，麻烦高手给看看。

function [sys,x0,str,ts] = dtcfunc1(t,x,u,flag)

switch flag==3,
  %%%%%%%%%%%%%%%%%%
  % Initialization %
  %%%%%%%%%%%%%%%%%%
  case 0,
    [sys,x0,str,ts]=mdlInitializeSizes;
  %%%%%%%%%%%
  % Outputs %
  %%%%%%%%%%%
  case 3,
    sys=mdlOutputs(t,x,u);
   case {1,2,4,9},
    sys=[];
  %%%%%%%%%%%%%%%%%%%%
  % Unexpected flags %
  %%%%%%%%%%%%%%%%%%%%
  otherwise
    error(['Unhandled flag = ',num2str(flag)]);
end

function [sys,x0,str,ts]=mdlInitializeSizes

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);
x0  = [];
str = [];
ts  = [0.001 0];

function sys=mdlOutputs(t,x,u)
u=round(u);
switch u
    case 1;
        sys(1)=0;sys(2)=1;sys(3)=1;
    case 2;
        sys(1)=0;sys(2)=0;sys(3)=1;
    case 3;
        sys(1)=1;sys(2)=0;sys(3)=1;
    case 4;
        sys(1)=1;sys(2)=0;sys(3)=0;
    case 5;
        sys(1)=1;sys(2)=1;sys(3)=0;
    case 6;
        sys(1)=0;sys(2)=1;sys(3)=0;
    case 0;
        sys(1)=0;sys(2)=0;sys(3)=0;
    otherwise
        sys(1)=0;sys(2)=0;sys(3)=0;
end
%
function sys=mdlGetTimeOfNextVarHit(t,x,u)
sampleTime = 1;    %  Example, set the next hit to be one second later.
sys = t + sampleTime;

function sys=mdlTerminate(t,x,u)
sys = [];

yg0060

把这个改改看怎么样
sizes.DirFeedthrough = 1;
因为你的方程没有状态变量，输出是由输入直接控制的。

nihaojiayafei

单独运行S函数是会报错，但是和Simulink结合仿真就没事了