Why FixedStep is not really fixed in simulink?

Hi ,

I was trying to sum outputs of two simulink models. For that, I choosed FixedStep = 0.05 for both,

But results shows two different time array ! So we can not sum up them.

Here is code (Simulink files are attached):

x = [-0.8506 ,-0.4860 ,1.2459,...
    -0.07146 ,46.7021 ,2.60395]; %Parameter #1 for simulink

un = zeros (1,12) ;             % Parameter #2 for simulink



Duration = [0 150];
options  = simset('FixedStep','0.05','SrcWorkspace','current','DstWorkspace','current','solver','ode45','ReturnWorkspaceOutputs','on');
a = sim('VL_u1',Duration,options);
b = sim('VL_u2',Duration,options);

Answer 1

[Fangjun Jiang]

It conflicts with your solver specification. ode45 is a variable-step solver.

FixedStep - Fixed step size [ positive scalar ]

FixedStep applies only to the fixed-step solvers. If there are discrete

components, the default is the fundamental sample time; otherwise, the

default is one-fiftieth of the simulation interval.

[Armin Mashhadi]

Thanks a lot ,

Got it !