I'm using Simevents and can't change the random seed in the Event Generator.

I've added a iterSeed generator in the InitFcn* callback...

disp('Changed random seed to')
iterSeed = randi(400)

And in the Event Generator I want to test how dt = randi([1 3]) varies with different seeds to change to see how a different random string plays out....

I've tried all the suggested approachs below, but none seem to work.

persistent rngInit;
%if isempty(rngInit)
 %   disp('Changed seed inside Entity Gen to:')
  %  iterSeed
   % rngInit = true;
%end

persistent rngInit;

if isempty(rngInit)
    fid = fopen('/dev/random');
    rndval = fread(fid,1,'uint32')
    fclose(fid);
    seed = rndval(1);
    rng(seed);1
    rngInit = true
end
dt = randi([1 3])
%persistent rngInit;
%if isempty(rngInit)
%    rng(iterSeed);
%    disp('Changed seed inside Entity Gen to:')
%    iterSeed
%    rngInit = true;
%end

%persistent rngInit;
%if isempty(rngInit)
%    seed = 12345;
%    rng(seed);
%    rngInit = true;
%end

Answer 1

[Altaïr]

Hey @Andrew Rutter,

A variable in the base workspace can be used to store the seed value and then applied within the Entity Generator. Here's how this can be done:

First, create a variable named 'seedVal' in the base workspace, and set it to the seconds value of the current system time with the following line:

seedVal=second(datetime())

Then, use these lines in the Intergeneration time action code field of the Entity Generator:

persistent rngInit;
if isempty(rngInit)
    rng(seedVal);
    rngInit = true;
end

dt = randi([1 3]);

This setup allows the intergeneration time to vary with simulation time as well as with the seed value.

For more detailed information on specifying intergeneration times, refer to this link: https://www.mathworks.com/help/releases/R2024a/simevents/ug/specifying-intergeneration-times-for-entities.html