function [sys,x0,str,ts,simStateCompliance] = sfunction_object(t,x,u,flag)
switch flag,
case 0,
[sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes;
case 1,
sys=mdlDerivatives(t,x,u);
case 2,
sys=mdlUpdate(t,x,u);
case 3,
sys=mdlOutputs(t,x,u);
case 4,
sys=mdlGetTimeOfNextVarHit(t,x,u);
case 9,
sys=mdlTerminate(t,x,u);
otherwise
DAStudio.error('Simulink:blocks:unhandledFlag', num2str(flag));
end
function [sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes
sizes = simsizes;
sizes.NumContStates = 2;
sizes.NumDiscStates = 0;
sizes.NumOutputs = 1;
sizes.NumInputs = 1;
sizes.DirFeedthrough = 1;
sizes.NumSampleTimes = 1; % at least one sample time is needed
sys = simsizes(sizes);
x0 = [0 0];
str = [];
ts = [0 0]; %对应纯连续系统
simStateCompliance = 'UnknownSimState';
function sys=mdlDerivatives(t,x,u) %连续系统计算导数
sys(1) = x(2); %对应于系统的状态空间方程式
sys(2) = -(25+10*rands(1))*x(2)+(133+30*rands(1))*u; %把计算得出的导数向量赋值给sys变量
function sys=mdlUpdate(t,x,u) %更新离散系统状态
sys = []; %本例为连续时间系统，该部分代码无需修改
function sys=mdlOutputs(t,x,u)
sys = x(1);
function sys=mdlGetTimeOfNextVarHit(t,x,u) %该子程序只在离散采样系统有用
sampleTime = 1; % Example, set the next hit to be one second later.
sys = t + sampleTime;
function sys=mdlTerminate(t,x,u)
sys = [];
