function [sys,x0,str,ts,simStateCompliance]=sfuntmpl(t,x,u,flag)%SFUNTMPL General MATLAB S-Function Template
% With MATLAB S-functions, you can define you own ordinary differential
% equations (ODEs), discrete system equations,and/or just about
% any type of algorithm to be used within a Simulink block diagram.%% The general form of an MATLAB S-function syntax is:%[SYS,X0,STR,TS,SIMSTATECOMPLIANCE]=SFUNC(T,X,U,FLAG,P1,...,Pn)%% What is returned by SFUNC at a given point in time, T, depends on the
% value of the FLAG, the current state vector, X,and the current
% input vector, U.%% FLAG RESULT DESCRIPTION
%-------------------------------------------------------%0[SIZES,X0,STR,TS] Initialization,return system sizes in SYS,% initial state in X0, state ordering strings
% in STR,and sample times in TS.%1 DX Return continuous state derivatives in SYS.%2 DS Update discrete states SYS =X(n+1)%3 Y Return outputs in SYS.%4 TNEXT Return next time hit for variable step sample
% time in SYS.%5 Reserved for future (root finding).%9[] Termination, perform any cleanup SYS=[].%%% The state vectors, X and X0 consists of continuous states followed
% by discrete states.%% Optional parameters, P1,...,Pn can be provided to the S-function and% used during any FLAG operation.%% When SFUNC is called with FLAG =0, the following information
% should be returned:%%SYS(1)= Number of continuous states.%SYS(2)= Number of discrete states.%SYS(3)= Number of outputs.%SYS(4)= Number of inputs.% Any of the first four elements in SYS can be specified
% as -1 indicating that they are dynamically sized. The
% actual length for all other flags will be equal to the
% length of the input, U.%SYS(5)= Reserved for root finding. Must be zero.%SYS(6)= Direct feedthrough flag (1=yes,0=no). The s-function
% has direct feedthrough if U is used during the FLAG=3% call. Setting this to 0 is akin to making a promise that
% U will not be used during FLAG=3. If you break the promise
% then unpredictable results will occur.%SYS(7)= Number of sample times. This is the number of rows in TS.%%% X0 = Initial state conditions or[]if no states.%% STR = State ordering strings which is generally specified as [].%% TS = An m-by-2 matrix containing the sample time
%(period, offset) information. Where m = number of sample
% times. The ordering of the sample times must be:%% TS =[00,: Continuous sample time.%01,: Continuous, but fixed in minor step
% sample time.% PERIOD OFFSET,: Discrete sample time where
% PERIOD >0& OFFSET < PERIOD.%-20];: Variable step discrete sample time
% where FLAG=4 is used to get time of
% next hit.%% There can be more than one sample time providing
% they are ordered such that they are monotonically
% increasing. Only the needed sample times should be
% specified in TS. When specifying more than one
% sample time, you must check for sample hits explicitly by
% seeing if%abs(round((T-OFFSET)/PERIOD)-(T-OFFSET)/PERIOD)% is within a specified tolerance, generally 1e-8. This
% tolerance is dependent upon your model's sampling times
%and simulation time.%% You can also specify that the sample time of the S-function
% is inherited from the driving block. For functions which
% change during minor steps,this is done by
% specifying SYS(7)=1and TS =[-10]. For functions which
% are held during minor steps,this is done by specifying
%SYS(7)=1and TS =[-11].%% SIMSTATECOMPLIANCE = Specifices how to handle this block when saving and% restoring the complete simulation state of the
% model. The allowed values are:'DefaultSimState',%'HasNoSimState'or'DisallowSimState'. If this value
% is not speficified, then the block's compliance with
% simState feature is set to 'UknownSimState'.% Copyright 1990-2010 The MathWorks, Inc.%% The following outlines the general structure of an S-function.%switch flag,%%%%%%%%%%%%%%%%%%% Initialization %%%%%%%%%%%%%%%%%%%case0,[sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes;%%%%%%%%%%%%%%%% Derivatives %%%%%%%%%%%%%%%%case1,sys=mdlDerivatives(t,x,u);%%%%%%%%%%% Update %%%%%%%%%%%case2,sys=mdlUpdate(t,x,u);%%%%%%%%%%%% Outputs %%%%%%%%%%%%case3,sys=mdlOutputs(t,x,u);%%%%%%%%%%%%%%%%%%%%%%%% GetTimeOfNextVarHit %%%%%%%%%%%%%%%%%%%%%%%%case4,sys=mdlGetTimeOfNextVarHit(t,x,u);%%%%%%%%%%%%%% Terminate %%%%%%%%%%%%%%case9,sys=mdlTerminate(t,x,u);%%%%%%%%%%%%%%%%%%%%% Unexpected flags %%%%%%%%%%%%%%%%%%%%%otherwiseDAStudio.error('Simulink:blocks:unhandledFlag',num2str(flag));end% end sfuntmpl%%=============================================================================% mdlInitializeSizes
% Return the sizes, initial conditions,and sample times for the S-function.%=============================================================================%
function [sys,x0,str,ts,simStateCompliance]=mdlInitializeSizes%% call simsizes for a sizes structure, fill it in and convert it to a
% sizes array.%% Note that in this example, the values are hard coded. This is not a
% recommended practice as the characteristics of the block are typically
% defined by the S-function parameters.%
sizes = simsizes;sizes.NumContStates =0;
sizes.NumDiscStates =0;
sizes.NumOutputs =0;
sizes.NumInputs =0;
sizes.DirFeedthrough =1;
sizes.NumSampleTimes =1;% at least one sample time is neededsys =simsizes(sizes);%% initialize the initial conditions
%
x0 =[];%% str is always an empty matrix
%
str =[];%% initialize the array of sample times
%
ts =[00];% Specify the block simStateCompliance. The allowed values are:%'UnknownSimState',< The default setting; warn and assume DefaultSimState
%'DefaultSimState',< Same sim state as a built-in block
%'HasNoSimState',< No sim state
%'DisallowSimState'< Error out when saving or restoring the model sim state
simStateCompliance ='UnknownSimState';% 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 =[];% end mdlUpdate%%=============================================================================% mdlOutputs
% Return the block outputs.%=============================================================================%
function sys=mdlOutputs(t,x,u)sys =[];% end mdlOutputs%%=============================================================================% mdlGetTimeOfNextVarHit
% Return the time of the next hit forthis block. Note that the result is
% absolute time. Note that this function is only used when you specify a
% variable discrete-time sample time [-20] 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
