function [sys,x0,str,ts] = addsig_s(t,x,u,flag)%%   The general form of an M-File S-function syntax is:%       [SYS,X0,STR,TS] = SFUNC(T,X,U,FLAG,P1,...,Pn)%%   Optional parameters, P1,...,Pn can be provided to the S-function and%   used during any FLAG operation.switch flag,  case 0,    [sys,x0,str,ts]=mdlInitializeSizes;  case { 1, 2, 4, 9 }    sys=[];		% Unused flags  case 3,    sys=mdlOutputs(t,x,u);  otherwise    error(['Unhandled flag = ',num2str(flag)]);end%%=============================================================================% mdlInitializeSizes% Return the sizes, initial conditions, and sample times for the S-function.%=============================================================================%function [sys,x0,str,ts]=mdlInitializeSizes% call simsizes for a sizes structure, fill it in and convert it to a% sizes array.sizes = simsizes;sizes.NumContStates  = 0;sizes.NumDiscStates  = 0;sizes.NumOutputs     = 1;sizes.NumInputs      = 2;sizes.DirFeedthrough = 1;sizes.NumSampleTimes = 1;   % at least one sample time is neededsys = simsizes(sizes);x0  = [];		% No continuous statesstr = []; 	% str is always an empty matrix, reserved for future use by Simulinkts  = [0 0];	% initialize the array of sample times% end mdlInitializeSizes%=============================================================================% mdlOutputs% Return the block outputs.%=============================================================================function sys=mdlOutputs(t,x,u)  getinvar    % Gets the input variables "inVar1","inVar2" from the previous    % Simulink block.  outVar1 = addsig(inVar1,inVar2);    % Calculate the number of sources by a DBT function (aic.m).  putoutvarclear    % Clear the variables "inVar1" and "inVar2" and puts the output    % variable "outVar1"    % to the next Simulink block.% end mdlOutputs