Implementing While loop in Simulink

Hello!

I am basically trying to implement a method for determining the attitude of a satellite in space in Simulink. The method uses a Newton-Raphson scheme to search for the optimum value. I figured out that the While Iterator can be used and have figured that the first line of the below code will basically act as the Initial condition to the While Iterator. I am having a problem trying to figure out the implementation of body of the while loop.

Any help with respect to that will be appreciated. Thanks!

lambda = sum(w); % Shuster1981 and markley1993
last_lambda = 0.0;
while abs(lambda - last_lambda) >= tolerance
    last_lambda = lambda;
    
    f = lambda^4 - (a + b)*lambda^2 - c*lambda + constant;
    f_dot = 4*lambda^3 - 2*(a + b)*lambda - c;
    lambda = lambda - f/f_dot;
end

[Ankit]

have you tried using While Iterator ?

Answer 1

[Sulaymon Eshkabilov]

Simulink 4 has [While Iterator Subsystem] that can be employed for NR simulation model.

Answer 2

[Jonas]

https://nl.mathworks.com/help/ecoder/ug/while-loop.html

The documentation demonstrates

• the While Iterator subsystem
• and alternatively if you have Stateflow, a Stateflow implementation
• and finally an embedded MATLAB Function implementation.

Maybe this last option is nice for you since you already have an implementation in MATLAB code.