Adding random noise in different timestep while numerical integration

How can I add a "random factor" only in every second integration step?

Because maybe I don't want to add the Random all the time - for example I Want to add it in time steps = 0.004 or maybe 0.008.

    dt = 0.002;
    end_1 = 2.0;
    time = 0:dt:end_1;

    Matrix = zeros(10,length(time);
    Matrix(:,0.5/dt:0.6/dt) = repmat(...);
    Random = randn(10,length(time);
    Matrix = Matrix + Random;

what is the best way to add Random in a different tilmestep than dt?

This dt = 0.002 will later serve as an integration step for solving a differential equation where matrix occurs - now, however, I would like to add the random component in, for example, coarser time steps (every 2nd ... or possibly only every 10th step).

Answer 1

[Dongyue]

Hi Thomas,

You can use mod() function as a flag, to trigger the adding ramdom process.

if mod(time, 0.04)==0
    Matrix = Matrix + Random;
end

For detailed information of mod() function, please go through the link below:

https://www.mathworks.com/help/matlab/ref/mod.html

Best,

Dongyue