How to create a persistent variable in the matlab function block inside simulink?

What is a best way to create a persistent variable in the matlab function block inside simulink? So that the values inside that variable can be changed insude the matlab function block at a simulation time step, and the new value is available at the next simulation step when the function is run again.

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/309929-using-persistent-vars-in-custom-simulink-matlab-function

But see also https://www.mathworks.com/matlabcentral/answers/285853-persistent-variable-clear-after-simulation-with-simulink#answer_223444

[Anoop Grewal]

Thank you very much Walter!