How to do for loop in m-function using SIMULINK

I want to do iteration loop in the m-function script using p-type ILC method update.

How can i implement for loop for 20 times and store in the Xd,i+1(t) which is the next state, e is the error signal and xd,i(t) is the present state. Eq is given below

Please help.

[Nitesh]

Any type of help will be appreciated.

Thank you