sfun_gain.m

《matlab使用详解》的部分源码

function [sys,x0,str,ts] = Sfun_Gain(t,x,u,flag,k)
%在主函数中修改函数名称，并修改文件名使其与函数名称对应
% The following outlines the general structure of an S-function.
switch flag,

 case 0,
    [sys,x0,str,ts]=mdlInitializeSizes(k);
  

  case 1,
    sys=mdlDerivatives(t,x,u);

  case 2,
    sys=mdlUpdate(t,x,u);


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


  case 4,
    sys=mdlGetTimeOfNextVarHit(t,x,u);

  case 9,
    sys=mdlTerminate(t,x,u);

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

end

% end sfuntmpl

%=============================================================================
% mdlInitializeSizes
% Return the sizes, initial conditions, and sample times for the S-function.
%=============================================================================
%
function [sys,x0,str,ts]=mdlInitializeSizes(k)

%初始化：在mdlInitializeSizes中，确定输入和输出数目。
%对于带有至少一个输入和输出的简单系统，它总是直接馈通的。
sizes = simsizes;

sizes.NumContStates  = 0;
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);

% initialize the initial conditions
x0  = [];
% str is always an empty matrix
str = [];
% initialize the array of sample times
ts  = [0 0];

% end mdlInitializeSizes

%
%=============================================================================
% mdlDerivatives
% Return the derivatives for the continuous states.
%=============================================================================
%
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 = [];

%=============================================================================
% mdlOutputs
% Return the block outputs.
%=============================================================================
%在mdlOutputs函数中，编写输出方程，并通过变量sys返回。
function sys=mdlOutputs(t,x,u,k)

sys = k*u;

% 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 = [];

% end mdlTerminate