Algebraic Loops in MATLAB

Hi all,

I am familiar with the concept of Algebraic Loops and the methods to solve them.

I am working on a project that requires translating a Simulink model to .m files. In this model, we have an algebraic loop, and for me it's not clear how I would implement this in standard .m files, or if (and how) MATLAB would be able to solve it. Do I need to formulate a specific nonlinear optimization problem in MATLAB or can MATLAB somehow identify the loop (as simulink does) and solve it using a suitable solver?

Answer 1

[Swastik Sarkar]

Hi @Goncalo,

The following MATLAB documentation provides details on how Simulink solves algebraic loops: https://www.mathworks.com/help/simulink/ug/algebraic-loops.html#bsn46y8-2.

Simulink utilizes trust-region or line-search methods to solve algebraic loops, which may require the Optimization Toolbox. More information on these methods can be found here:

• Trust-region: https://www.mathworks.com/help/optim/ug/unconstrained-nonlinear-optimization-algorithms.html#brnpcy5
• Line search: https://www.mathworks.com/help/optim/ug/unconstrained-nonlinear-optimization-algorithms.html#f15468

The fminunc function can be particularly useful in this context.

Hope this helps