Differential equation by simulink

Hello everyone,

I modeled a differential equation by simulink. My question is that what is the simulink assumption for initial conditions (necessary to compute the constants, c1 and c2):

For example a typical equation with solution is:

the simulink model is

The simulink result is

I cannot make a comparison between the analytical result and simulink result! I'm not sure if simulink works well... what is the initial condition assumed by simulink and what are the solution constants (c1 and c2)?

Answer 1

[Mischa Kim]

Double-klick on the integrator blocks and you'll see that the default initial condition is zero (0). It is also inside the integrator block where you change the intial condition, or, select that it is defined through an external input.

Also, I noticed in your model that the feedback loop starts after the second integrator, while your differential equation contains a Xdot. To make the Simulink model consistent with the equation the loop would have to start between the first and second integrator.

[Si So]

That's right..., very helpfullllllll feedback, thanks Mischa