Hi Akram

First, you must convert the differential equations to their difference form.

For example dx/dt will be converted to

(X(k)- X(k-1))/Ts

Which k is the current and (k-1) is the previous sampling time. Also Ts is the sampling time.

Habib M. N. Ahmad

thanks for your answer, I already use this block but my question is little bit deeper related to modeling, not only state space matrix.

** advice of the idea of "using" the discrete state space if it is important in my application.

** and if I can have a discrete rate of change as input "u" and how to implement it.

Thank you

Hi Akram

First, you must convert the differential equations to their difference form.

For example dx/dt will be converted to

(X(k)- X(k-1))/Ts

Which k is the current and (k-1) is the previous sampling time. Also Ts is the sampling time.

Farhad Yazdi thanks .. shall I do it manually on Simulink, or I use "discrete derivative block"?

also can the input u be differential parameter ??!!

@ Akram Elhelbawy

The most flexible and stright forward method is using s-functions in your simulink. In this way you can mix the abilities of both simulink and coding.

In theory yes U can be anything. You can consider any non-linear equation in your plant. But in the state space form, the answer is no. So, You must change and/or simpify it in its exact format.