MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur télécharger pdf (Page 42)

2 Writing S-Functions As M-Files

2-18

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

% This example S-function illustrates how to create a variable

% step block in Simulink. This block implements a variable step

% delay in which the first input is delayed by an amount of time

% determined by the second input:

% dt = u(2)

% y(t+dt) = u(t)

switch flag,

case 0

[sys,x0,str,ts] = mdlInitializeSizes; % Initialization

case 2

sys = mdlUpdate(t,x,u); % Update Discrete states

case 3

sys = mdlOutputs(t,x,u); % Calculate outputs

case 4

sys = mdlGetTimeOfNextVarHit(t,x,u); % Get next sample time

case { 1, 9 }

sys = []; % Unused flags

otherwise

error(['Unhandled flag = ',num2str(flag)]); % Error handling

end

% End of vsfunc.

%==============================================================

% 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.

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MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur Page 42